Process for providing an improved drilling fluid and the product thereof



March 2, 1965 STORMER VISCOSITY 0F CLAY- WATER DR\LLIN6 FLU) E. G. KING ETAL PROCESS FOR PROVIDING AN IMPROVED DRILLING FLUID AND THE PRODUCT THEREOF Filed Oct. 23, 1958 MIXTURES OF PHOSPHATES AND THINNER OF OUR INVENTION 0.5*"/BBL. AT PH 9.5 m Wvomms BENTONkTE Mun A650 24 Has. AT 150 F.

60 JZ EE LS'iQ VBBL. PH 9.5

A= somuM PYROPHOSPHATE E B=x SODIUM TETRAPHOSPHATE C=+ SODIUM HEXAMETAPHOSPHATE- D= SODIUM ACID PYROPHOSPHATE E= SODIUM TRIPOLYPHOSPHATE o \0 20 so 4 5o 60 PERCENT OF COMPLEX PHOSPHATE IN MIXTURE (419. J INVENTORS ELL/S GRHY KING Y CflRL HDOLPHSON a-ldl/ ATTORNE Y- United States Patent PROCESS FOR PROVHDENG AN IIt EPRGVED DRELL- ING FLUID AND THE PRODUCT TEEREOF Ellis Gray King and Carl Adolphson, Bellingham, Wash, assignors to Georgiahacific Corporation, Portland,

Oreg, a corporation of Georgia Filed Oct. 23, 1958, Ser. No. muss 28 Claims. (Cl. 252-65) Our invention and discovery relates to improvements in drilling fluids resulting from a novel combintaion of clays and specially treated sufonated lignin containing material derived from spent wood pulping liquors.

This application is a continuation-in-part of application S.N. 539,542, filed October 10, 1955, now US. Patent No. 2,935,504.

More particularly our invention relates to an improved drilling fluid or mud combination. This mud combination may be formulated to function as fresh water mud, as lime base mud, as salt contaminated or sea Water muds, and as emulsion systems. Furthermore, the mud combination is usable over the entire pH range of drilling mud fluids used in the field. A particularly novel form of our mud system is the combination with gypsum which is especially useful in drilling oil wells when anhydrite is encountered. Heretofore, a Well recognized fact is that additives derived from spent sulfite liquor in lime base muds but such are not useful in fresh water muds.

Moreover, our improved mud combination is characterized by stability to high temperature and by efi'ectiveness in resisting the deteriorating effects of contaminants encountered in drilling. Such effectiveness is particularly advantageous in drilling deep wells where high temperature and pressure exists.

Our invention and discovery herein relates primarily and fundamentally to the providing of a novel combination of drilling mud clay and sulfonated lignin containing material whereby there results drilling muds of newly found properties. discovery as applied to combination for use as drilling muds, however, we intend to include all applications Where like requirements exist in whole or in part, particularly Where an impervious wall or liner is involved as in a canal lining for aqueducts such as used in irrigation or otherwise. It would be difiicult to find a more sensitive test of the increased effectiveness of the components of our invention than those required to meet the proper ties of said drilling muds.

The improved effectiveness of the components of the spent sulflte liquor provides for their use such as a drilling mud additive or as the base from which an improved drilling mud can be formed, which mud is characterized by having greatly improved properties.

The outstanding properties of suitable magnitude which characterize a suitable drilling mud comprise the following: (1) initial gel strength; (2) suitable viscosity; (3) -minute gel strength; and (4) Water loss, which relates to the sealing off of the wall of the drilling hole by building up a filter cake of mud on the wall, thus preventing loss of water from the mud. Thus, it is manfest that the drilling mud, with its exacting requirements of various properties for the mud is a most important, involved, and complex feature of oil and gas Well drilling Universally, a drilling mud (having about the consis- While we set forth our invention and tency of lubricating oil) is used in a circulating system with rotary well drilling mechanism, and is forced by pumping down the hollow drill stem through the bit which it lubricates and cools, then back to the surface to a settling pit. Thus it washes out the cuttings which have been made from the hole, and the cuttings are carried outside the drill stem to the surface where the coarse particles are caused to be removed and the mud again used in a continuous circulating process. To. prevent the loss of the mud in porous strata, the mud must be of a character to seal off such strata and the mud, by its hydrostatic pressure, must prevent the escape of gas, that is, prevent the Well from blowing out. To provide the proper hydrostatic pressure, the specific gravity of the mud may be increased by adding heavier material than clay, such as barytes. On the one hand the drilling fluid must have viscosity, that is, be thick enough to carry out the cuttings, but thin enough to be pumped and to allow the coarse particles to settle out in the surface mud pits so that the mud may be re-used.

One of the more specific features of our invention and discovery relates to the process for the preparation of a drilling mud additive from spent sulfite liquor which preferably has been concentrated and preferably has part at least of its carbohydrates removed by fermentation treatment or otherwise. This product is the drilling mud additive to be combined with the drilling mud clay to form the improved drilling mud fluid.

Broadly, the starting material for our purpose is a sulfonated lignin containing material derived from wood pulping liquors irrespective of how it may be prepared.

Our invention and discovery is characterized by making it possible to greatly improve the effectiveness of the components of said sulfonated lignin containing material with very simple and inexpensive equipment. The simplicity of the treatment of our invention and discovery is one of its outstanding features.

In case of temporary stoppage of work, the mud should gel sufliciently to prevent settling of the suspended cuttings, which settled cuttings would seize the drill stem and prevent re-starting or its withdrawal from the well. From this it is manifest that the viscosity of the fluid is highly important. Likewise, the property to gel or set like gelatin is important when the agitation incident to drilling ceases. Thus, the mud will hold in suspension the cuttings and at the same time become fluid when agitation is resumed. This is called the thiXotropic property of the fluid, or its gel strength. Most clays have this property but not all. Such property may be increased by adding the clay called bentonite and similar substances. As the drilling proceeds through different strata, the viscosity and gel strength may be affected by the character of the strata, by the loss by absorption of Water in the porous strata or the iii-flow of water and other fluids, by the temperature changes, or by chemically active substances which may enter the drilling fluid as the drilling proceeds. Accordingly, viscosity, gel and water loss are very carefully watched and corrected from time to time during the drilling. There are instruments provided for testing such properties at the mouth of the well.

In the early history of well drilling, water was added to thin the mud, but this had the objectionable result of reducing the specific gravity of the drilling fluid and thereby decreased its hydrostatic pressure property, and

3 also decreased its ability to suspend the cuttings and the barytes which had been added to give weight. Also, to overcome the effect of addition of chemicals from the strata through which the well proceeded, i.e., the effect from so-called contaminants, other chemicals were added to offset the deleterious effects.

In fact, the literature relating to drilling muds is so extensive and comprehensive and has extended over such a long period of time that it is very apparent that important difficulties, mechanical, chemical, and economical, are involved in the controlling, conditioning, and obtaining of the proper type of drilling mud. It is one of the fundamental objects and purposes of this invention and discovery to provide a process for making an inexpensive and highly effective mud additive to overcome the problems that have existed for so long in this field. Let it always be kept in mind that the value of the drilling mud depends on how much it will contribute to speed, efficiency, and safety in oil and gas well drilling. Our invention and discovery provides a combination of clay and treated sulfonated lignin containing material, which combination is characterized by its economy as well as its very special effectiveness, not only for one of the two primary recognized types of drilling muds, i.e., lime base and fresh water muds, but for the special effectiveness of both of said types of muds.

An important and fundamental object of our invention is to provide a gypsum base mud characterized by a low gel rate rather than the usual objectionable high gel rate which is usually accompanied by high fiat gels. Such muds accomplish the maintaining of suitable gels so that cuttings fall out in the mud pit without the necessity of watering back to thin the mud. In this way, the need for costly water loss reducing agents such as carboxymethylcellulose is substantially lessened, if not eliminated, and the amount of expensive weighting agents required for deep wells is decreased.

Relative contaminants In the drilling of deep wells such as oil and gas by the employment of a mud laden drilling fluid as in the rotary system of drilling, strata of a contaminating character may be encountered in large masses which often supply calcium sulfate to the drilling mud-this is very disadvantageous and alters or destroys required properties of the mud. Such calcium sulfate may be, among other forms, in the form of gypsum (calcium sulfate with water of crystallization) and anhydrite (calcium sulfate without water of crystallization). The literature states (Rogers Composition and Properties of Oil Well Drilling Fluids, page 377):

The first small additions of calcium sulfate increase the viscosity and gel strength of the mud fluid greatly but do not increase the fluid loss appreciably. This peak portion of the viscosity curve is reached at an addition of 33.3 ppm. calcium per gram of bentonite. As the concentration of calcium sulfate increases, the viscosity decreases and the fluid loss increases sharply.

As the concentration of the calcium sulfate increases, the viscosity decreases and the fluid loss increases sharply--obviously this feature evidences unpredictable character of contaminants upon the components of the drilling muds as respects the important properties which must characterize the mud. The different properties of the mud are affected differently. Rogers further states (said text, page 378) unfortunately, the addition of the soluble sodium sulfate results in a large increase in viscosity and gel strength. This effect is of such a magnitude that the method cannot be used in the field to overcome the ad verse effects of the anhydrite. It can, however, be demonstrated in the laboratory.

The discovery and invention herein disclosed shows how this objectionable feature of sodium sulfate has been overcome, and to this extent the invention and discovery of applicants is contrary to the recognized literature in this field.

Other contaminating strata are salt beds and the cement employed in the construction of the well. Also let it be noted that the contaminants may be a combination of the contaminants disclosed herein.

It is the primary and fundamental purpose of our inventi-on and discovery to provide a drilling mud system or combination of clay and sulfonated lignin containing material which will operate in controlling the colloidal and physical properties and for maintaining the required properties of a water-clay drilling mud which may be subject to contaminats, so that the mud combination will function in a more effective and more economical manner than heretofore. Thus, an important part of our invention is the rendering more effective the properties of the sulfonated lignin containing materials and herein resides protection against contamination.

This part of our invention relating to the sulfonated lignin containing materials is commonly referred to as the drilling mud additive. Our purpose is to provide such an additive of a character which will function as a control product for the colloidal and physical properties and for maintaining the required properties of the water clay drilling mud which may become subject to contaminants in the drilling operation and to provide such an additive when combined with the mud that will function in a more efiicient and more economical manner than has been accomplished heretofore.

Accordingly, we now proceed to set forth the process part of our invention relative to the improvement of the effectiveness of the sulfonated lignin containing material.

Stated in its simplest form, this anti-contamination part of our invenion and discovery involves the addition of sodium sulfate or equivalents as hereinafter listed to the combination of clayey material and the additive lignosulfonate product of our invention and discovery, in the proportion of 1% to by weight of the additive lignosulfonate product, said addition being made in proportions determined by a pilot test of a drilling mud which has encountered contaminants. The additive product of our invention in and of itself may not produce the extremely low water losses desired in some muds. The addition of the sodium sulfate and equivalents as hereinafter listed will further reduce the water loss to the desired level and at the same time said additive product prevents the large rise in viscosity and gel factors which occur when sodium sulfate alone is added to an aqueous suspension of clayey material. Thus in the presence of the additive lignosulfonate product, the ordinary adverse action of the sodium sulfate is depressed.

Sometimes the formations are of thick dolomitic lime or other rock sections which do not contribute good mud making materials. In such cases it is necessary to control or maintain the mud by addition daily of bentonite to develop the desired low fluid loss, and the pH of the mud is maintained on the alkaline side to promote hydration and dispersion of the drilled shales. The alkaline pH promotes higher viscosities in the hentonite clays, and, therefore, thinners are added and those with alkaline properties such as the sodium tannate type are preferred. These thinners, because of the presence of alkaline sodium salt, aid in the formation of sodium clays from the dispersed shales and also increase the degree of dispersion of the clays and shales and hence reduce the fluid loss to strata surrounding the hole. In general, the pH or alkalinity of such muds is maintained at about 9.0 or 10.0. At times the pH of the mud rises or is carried to the range of 10.5 to 11.5 in which the clays and bentonite present manifest appreciably higher viscosity. The treatment of these muds is with sodium hydroxide and quebracho (sodium tannate), and they are referred to as red muds. In all of the cases, the principal contaminants are salt, cement, gypsum or anhydrite, sand, and other inert mineral matter.

When the mud viscosity becomes too high, it may be more economical to convert to the so-called lime base mud rather than to dilute with water involving the necessary addition of weighting material. At other times, the contamination becomes so bad that the chemicals are not elfective and it is found necessary to convert to the lime base mud. This conversion involves the addition of an excess of lime and caustic together with a thinner such as quebracho or, preferably, lignosulfonates. This type of high pH mud with an excess of lime is hereinafter referred to as a lime base mud as contrasted to all of the other water clay muds previously discussed, which for convenience will be hereinafter termed fresh Water muds.

Objects In general, quebracho, as a thinner, has been used in all types of rnuds, both fresh water and lime base, but quebracho is an expensive commodity. To date, the lignosulfonates have been useful only in lime base muds where they are well known to be relatively inexpensive, but until now, i.e., until this disclosure, it has not been possible to use the lignosulfonates in the lower pH (less than 12, i.e., fresh water) muds not containing an excess of lime, inasmuch as they have no appreciable thinning action on such muds. It is one of the purposes of this disclosure to describe products of our invention and discovery which are highly effective, not only as lime base muds, but also as fresh water type maas.

A primary and fundamental object is to provide a process for the modification of the spent wood pulping liquor solids in the simplest and most economical manner with relatively .inexpensive equipment, and in a continuous manner to produce from these said liquor solids an additive for drilling mud systems or combinations which is effective in reducing the viscosity and gels of both fresh water muds and the so-called lime base muds, even in the presence of substantial quantities of natural contaminants such as anhydrite, sodium chloride and sodium sulphate.

Another objective is to provide a sequence of steps whereby spent Wood pulping liquors are preferably initially purified and fractionated and then modified to obtain an additive for making the mud combination of our invention which is characterized by the fact that molecules of each fraction are of a particular and different molecular average size and especially useful for dispersing agents in general and additives for drilling muds in particular.

Another primary object of our invention is to provide a process for preparing and fractionating chlorinated lignosulfonates to provide said chlorlignosulfonates in fractions of specific molecular weight to adapt the same to a particular purpose. It is particularly the object of this invention to provide means for preparing spent sulfite liquor additives that are not only especially lower in cost, but are highly effective and useful in essentially all types of water clay and oil-in-water emulsion drilling muds.

Still another object of this invention is to provide a drilling mud which is prepared with saline or sea water when fresh water is not readily available. Mud prepared with sea Water has special utility in oif-shore drilling with fresh water must be transported to the drilling site and fresh Water muds must be protected from sea water contamination. We have found that the additive of our invention is surprisingly effective as a thinner not only for gypsum base muds, but also for saline mud-s made up originally with sea Water as the aqueous component together with commercial drilling mud clays.

Defining starting materials Spent lignin liquors from the pulping of wood are the basic raw material for our process and product, the

said liquors being available in large quantity as waste products of the pulping processes. One of our aims is to conserve this waste material.

The preferred raw material is derived from the pulping of Wood by the calcium bisulfite process for the manufacture of pulp. In this operation a substantial portion (20% to 70%, usually about 55%) of the wood is converted to water soluble products which at the end of the cooking process are separated from the pulp in water solution. This solution, because of the washings, is very dilute, ranging approximately from 5% to 20% solids. This solution can be used as such in our process or it can be concentrated in any one of several Well known ways to a more concentrated solution which is more readily and economically handled, particularly because of the smaller volume of liquid involved. The concentrated solution can range from 30% to 70%, but handles better in the range of 40% to 50% total solids in solution. This concentrated solution contains lignosulfonates as salts (for example calcium, magnesium, sodium, or ammonium salts, depending on which of these are employed in the digesting process), carbohydrates, and other complex organic compounds derived from wood, as well as inor anic compounds either present in the wood or derived from the reaction. Furthermore, digesting of Wood by iron or aluminum bisulfite will give a spent sulfite liquor component which may be our raw material and which will obviate the necessity of a base exchange reaction to form the iron or aluminum salts. The concentrated solution may be used in our invention and it is very desirable to do so. However, the spent sulfite liquor can be further refined before or after processing according to our invention. For example, the spent sulfite liquor can be essentially freed of carbohydrate material by any one of a number of procedures, preferably by fermentation. Also, said carbohydrates may be removed by dialysis, by separation with organic solvents or organic bases, or by precipitation as basic lignosulfonates, for example, with lime or by salting out with salts such as calcium chloride or sodium chloride. in addition, the lignosulfonates, as well as being freed as far as possible of extraneous materials, may be fractionated as to molecular Weight components by the process disclosed in the application Ser. No. 437,833, now abandoned, entitled Process for Separating and Fractionating Spent Sulfite Liquor Components of Pulp Digesting Processes by Grganic Solvents and Preparing Useful Products Therefrom. This process en ploys phase separation with alcohols without precipitation of inorganic compounds of the spent sulfite liquor.

Any of these above described products are basically derived from spent suiiite liquor solids, and are sulfonated lignin containing materials and the degree of refining to which they are subjected either before or after the steps of our invention will depend on the quality of product desired and the economics involved. That is, refining to some extent will improve the properties of the final processed product, but the degree of improvement will not always be economically justifiable. In fact, it is the essential and outstanding feature of our invention and discovery that We can use concentrated spent sulfite liquor as such, and through a series of simple steps involving equipment which is relatively inexpensive, can produce products which are equivalent in properties, for instance, for use as drilling mud additives and dispersants, to the purified lignosuifonates.

In general, any type of Wood which can be resolved to pulp by the suifite process or by the iron or aluminum bisuliite process, may be used in foilowing our invention. Furthermore, changes in the final properties of the prod uct are influenced by the conditions of the pulping process, but in general good results are obtained using the commercial spent suliite liquor from either paper grade quality puip or dissolving grade quality pulp.

In addition to the spent sulfite liquor derived from the acid bisulfite pulping of wood, liquors containing soluble lignin are also available from the neutral and alkaline pulping of wood. Such lignin containing materials may be converted to sulfonated lignin containing materials usable as raw materials for the process of our invention, for instance by treatment with sulfites at elevated temperatures, chlorination and heating with sodium sulfite or by other methods known to those skilled in the art, subject only to getting a soluble sulfonated lignin or one which tends to dissolve in water and which on forming the metallic salt and being oxidized is soluble. For example and not by way of limitation, sulfonated Kraft lignin has been found to perform well in making the oxidized metallic salts of sulfonated lignin according to our disclosure. This is also true of sulfonated soda lignin.

In deriving sulfonated lignin containing material from wood pulping liquors varying degrees of sulfonated lignin containing material results, depending on the well known range of conditions involved in the different methods of sulfonation. For practicing our invention the resulting sulfonated raw material should be soluble in water or in highly alkaline aqueous media and should have dispersing properties. These characteristics are associated with the degree of sulfonation, or the proportion of sulfonic acid groups which have entered the lignin molecule during the sulfonation process. The chemical formula for sulfonic acid groups is --SO l-I, in which the sulfur atom is combined directly with a carbon atom in the lignin or other organic material in the lignin containing material sulfonated. This type of sulfur is to be distinguished from inorganic sulfates or sulfites, sulfur dioxide free or loosely combined with the lignin and sulfur which might be bound with the lignin as a sulfate. The sulfonate sulfur or sulfur combined directly with carbon is a stabily bound sulfur which is not removed from the lignin without drastic treatment such as with sodium hydroxide at high temperature and pressure. In speaking of the sulfur content of the sulfonated lignin containing material, we refer to the total sulfur as the sulfur of all types which are determined by standard analytical procedures and to the sulfonate sulfur which is the sulfur stabily bound with the lignin. The degree of sulfonation required to promote solubility and dispersive properties will vary some what with the source of the lignin being sulfonated, i.e. the conditions of pulping, and sulfonated lignins ranging from 0.93.8 have been used successfully in making the dispersive additives of our invention. But in general it has been found that when the sulfonate sulfur content is less than 1% the product is unsuitable whereas above 4.5% the product is suitable.

By way of summary, the raw material for our process is a sulfonated lignin containing material as it may be received from the blow pit of the bisulfite process or modifications of said bisulfite process employing somewhat less acidity, for example and not limitation, about pH 4.5 instead of 1.5 or less, or other sulfonated lignin containing materials derived from neutral or alkaline pulping processes. Any of these may be in any one of a number of states or degrees of refinement, purification, and concentration. We prefer, however, to use concentrated and fermented spent sulfite liquor from the pulping of wood with calcium bisulfite cooking acid because such material is already sulfonated, and is easily converted to other metal salts as disclosed herein and is available in large quantities. By fermented is meant spent liquor from which carbohydrates have been removed by fermentation. In any event our starting material comprises a sulfonated lignin containing material.

Our starting material may be refined and fractionated, but whether it is fractionated before or after treatment according to our invention depends on economical considerations and the special product desired.

Briefly stated, our process in part involves converting sulfonated lignin containing material to a salt of iron, chromium, copper, and aluminum, or combinations of said salts; or converting the refined sulfonated lignin containing material to said salts; or converting the fractionated sulfonated lignin containing material to said salts; or converting to said metal salts sulfonated lignin material subjected to other pretreatments effecting improve ment in properties for use in drilling mud for example but not by limitation by alkaline heat pretreatment (see Ser. No. 694,737, now U.S. Patent No. 3,607,864), acid heat pretreatment (Ser. No. 723,036, now U.S. Patent No. 3,138,555) and pretreatment by steam stripping, gas or air blowing during heating of solutions of said sulfonated lignin containing material derived from spent wood pulping liquors.

Furthermore, our process involves subjecting the sulfonated lignin containing material containing said metallic salts to oxidation which brings about changes in the constitution of the solids of the sulfonated lignin containing material resulting in additives of greatly enhanced properties comparable and superior to those of natural quebracho in the making of drilling muds.

Also, liquor containing the said metallic salts of dissolved fractionated components also may be subjected to oxidation which brings about changes in the constitution of the fractionated solids of the sulfonated lignin containing materials resulting also in additives of greatly enhanged properties comparable and superior to those of natural quebracho in making drilling muds. Our products are also superior in dispersing the ingredients of clay slips, cement, plaster, etc.

The fact that the original spent sulfite liquor may be oxidized directly and converted to the said metallic salts, forming an additive which is effective in both fresh water and lime base muds, manifests how very economical may be the products of our invention for such special uses.

In making the salts of iron, aluminum, copper, or chromium of sulfite liquor either before or after oxidation, we prefer to use the sulfates of these elements for this purpose because with calcium base sulfite liquor, calcium sulfate precipitates so that if may be removed and thereby bring about purification of the product. Higher temperature promotes the growth of larger crystals of calcium sulfate which are easier to separate from the liquor, hence it is desirable to hold the liquor after addition of the sulfate at 90-95 C. for a period of time. The formation of large crystals is also fostered by bringing about the interaction of the salt with the spent sulfite liquor solids in such a manner that the precipitation of the calcium sulfate occurs more slowly. This objective can be accomplished by using more dilute solutions and/or using lower temperatures during the base exchange reaction. Hence, a preferred method of forming the iron, chromium, copper, and aluminum salts is to carry the reaction out at 3050 C. and then to heat the solution with agitation to 90-95 and hold this temperature for one hour or longer. This latter treatment is also an acid treatment and has beneficial action on the properties of the spent sulfite liquor product.

Aluminum sulfate may be added preferably in proportion equivalent to the base (i.e., calcium, sodium, magnesium and ammonium) already present in the spent sulfite liquor or it can be used in smaller or greater proportions. Furthermore, aluminum sulfate may be added in anhydrous form or as any of the hydrates of commerce, such as paper makers alum (17% A1 0 or as Prl2(SO4) 3 In making the lignosulfonate salts, we have used aluminum sulfate salts in the proportion of 1% to 50% by weight of the spent sulfite liquor solids. With the other salts, i.e., iron, chromium and copper, the range of permissible addition is about the same, i.e., 1% to 50%. For example, copper requires the addition of about 30% of CuSQySH O for complete base exchange as compared with about 26% of Al (SO -l3ll which takes into consideration the usual chemical equivalence. However, good results have been obtained in using from to of aluminum sulfate (Al (SO 18H O). The same observation applies to the use of iron, chromium, and copper salts.

In addition to adding sufficient of the cations to be equivalent to approximately the base present in the sulfonated lignin containing material, it is our unusual (and unexpected) discovery that an excess of the cation over the chemical equivalent for base exchange improves the elfectiveness of the product of our invention and discovery in respect to the conditioning of fresh water mud and in particular in obtaining the lowest possible values for yield value and 10 min. gel and water loss, but such excess has a deleterious effect on said properties of lime base muds. Thus in the preparation of fresh water muds, we prefer to add an excess of a sulfate salt having a cation selected from the group: Iron, aluminum, copper and chromium, or mixtures thereof. Since these salts occur as hydrates with varying amounts of water, the permissible addition of these salts to the mud is more definitely expressed as an amount of the sulfate salt equivalent to the anhydrous form of that salt. Thus in terms of the anhydrous for as, the permissible addition is about 1% to 80% in excess of amount of salt necessary for the base exchange. Thus, for example, with the ferric sulfate the optimum results are obtained with a total addition of the sulfate salt of about 40% to 50% by weight of the sulfonated lignin containing material, which, on the anhydrous basis, would be about to 42% by weight. Accordingly, the excess over the amount for chemical equivalents on the anhydrous basis is 20% to 27%. Ferrous sulfate and the sulfates of aluminum, chromium and copper perform in the same manner and the excess addition over the chemical on an anhydrous basis is also 1% to 89%. Mixtures of these sulfate salts can be used for this purpose. Copper has the advantage of imparting antiseptic properties to the additive, to preserve the mud which may be subject to microbiological attack, particularly so when starch is present.

in forming the said salts of the sulfonated lignin containing material, it is preferable to have the latter in the calcium condition, that is, as a calcium salt so that when the sulfate salts of iron, aluminum, copper and chromium are added, the base exchange reaction occurs and calcium sulfate forms which can be removed, thus yielding an essentially pure form of the desired salt.

In regard to the permissible addition of excess sulfate salt the disclosure above of l to 80% of the anhydrous sulfate salt pertains to the salt and not to the oxidized salt. For the latter see Table 3 of Example 1X.

However, any soluble salt of these metals could be added to a solution of the sulfonated lignin containing material without the formation and/or removal of a precipitate. When such a solution is brought to dryness, because of the ionic equilibrium in the solution, a mixture of salts is obtained. Thus an amount of the desired salt, for example, iron, would be present in the product, together with the base (sodium, magnesium, ammonium, etc.) which was originally in the sulfonated lignin containing material. This product would not be as eiiicient as the product in which the original base in the sulfonated lignin containing material was removed prior or on addi tion of the iron salts. However, in cases where the sulfonated lignin containin material has the base sodium, magnesium or ammonium present instead of calcium, it

my be satisfactory to sake the partial salt in the afor said manner. This could be the case, for example, with ulfonated lignin from the Kraft and soda processes which usually contains sodium as the base by reason of the steps of its manufacture.

When magnesium, ammonium, or sodium bisulfite cooking liquor instead of calcium has been used in manufacturing the pulp, it is'then desirable, but not absolutely necessary, to eliminate or partially eliminate the magnesium, ammonium, or sodium ions prior to making the iron, chromium, copper, or aluminum salt. This situation can be brought about by converting to the calcium salt before proceeding with the process of our invention, or it can be accomplished by any number of procedures well known to those skilled in the artfor example, by ion exchange, dialysis with addition of acids, and base exchange procedures in general. For example, cations (i.e., magnesium, ammonium, or sodium) may be removed by passing the liquor through a cation exchange column in the hydrogen state, and then treated with an oxide or hydroxide of iron, chromium, copper, or aluminum. We prefer to have the lignosulfonate in the form of the calcium salts before making the iron, chromium, copper, and aluminum salts because the salts are obtained with less contamination in this manner by reason of the calcium sulfate being precipitated so it can be removedbut note well, such purified products can be obtained by any procedure known to the art for making the conversion to the desired salt as well as those named immediately above.

For example, a special case of partial salt formation comes as a result of the treatment with sodium or potassium dichromate as a result of the fact that chromium salts are a product of the reactions involved. Any soluble chromium salts thus formed will provide chromium ions which will be in equilibrium with the calcium ions associated with the sulfonate group of the lignosulfonate. Thus, a partial chromium salt of the lignosulfonate in essence will be formed which would tend to impart the properties attained if the calcium were removed and the light:- sulfonate salt were Wholly chromium salts. If, furthermore, an excess over the amount of sodium dichromate necessary for the base exchange, is. about 12% of sodium dichromate, is added, additional chromium ions resulting from the reduction of the dichrornate are present which tend to drive the reaction in the direction of the formation of the chromium salt of the lignosulfonate so that this excess would have somewhat the effect of removing the calcium or in other Words, forming a chromium salt instead of the calcium salt of the lignosulfonate. T e addition of excess sodium dichrcmate, as a result of the chromium salts formed by the reduction of the dichromate, would also have somewhat the effect of the addition of an excess of chromium sulfate over that necessary to make the base exchange for the same reason. This method of forming the salts, however, does not yield a product which is as elfective for mud formulation as the methods previously described where calcium is removed, for example as the sulfate or otherwise, because calcium ions cause thickening of drilling mud and because of the miscellaneous reaction products. However, the effectiveness of agents made in this manner can be improved by removing the calcium during the treatment, for example, by adding sulfuric acid or any other acid whose anion forms insoluble salts with calcium or by addition of suitable salts which form insoluble compounds with calcium such as sodium sulfate. This illustration is mentioned by way of example that an improvement can be obtained by the presence of an excess of chromium, aluminum, copper, iron salts or combinations thereof, even though there is an equilibrium mixture present with other ions, such as potassium and sodium, but is not given to indicate a preferred method of operation.

It should be noted that an excess of sodium ions resulting from excess sodium dichromate addition is not particularly harmful since the drilling mud clays are also sodium salts and the addi ional sodium ions introduced into the mud by the additive are relatively few.

The iron, chromium, copper, and aluminum salts of the lignosulfonates thus formed are useful as drilling mud thinners in muds which do not contain an excess of lime, i.e., fresh water muds, these products are thereby distinguished from the spent sulfite liquor products previously used as thinners in the so-called lime base muds. These previous lignosulfonate thinners which may be ammonium, sodium, magnesium, or calcium salts of lignosulfonates are operable only in the lime base muds and are not etfective in muds which are sometimes termed fresh water muds, i.e. muds of low pH and which do not contain salts of aluminum, iron, copper and chromium. The inclusion of said salts being a part of our invention and discovery. The aluminum, iron, copper, and chromium salts of the spent sulfite liquor on the other hand are effective in varying degrees over the whole pH range of the fresh water muds and are also operable as thinners in lime base muds.

Furthermore, let it be noted that another alternate pretreatment may be used whereby the hot spent sulfite liquor is acidified and air blown or treated to remove the sulfur dioxide and then oxidized with the agents described below. By this course the spent sulfite liquor is purified of sulfur dioxide, and apparently the structure of the components of the spent sulfite liquor is modified and the oxidizing agents it later used are conserved for performing their special functions.

In general, the important feature of our invention and discovery is that the oxidation of spent sulfite liquor components leads to increased activity or enhanced properties of said components respecting dispersing properties, and that these changed properties are manifested in the thinning of the viscosity of clay suspensions and also in the reduction of the gel-like properties of such suspensions. We have found that most oxidizing agents are operable in varying degrees as to the improvement produced. Particularly eifective for this purpose are the following: Hydrogen peroxide, ozone, lead dioxide, chromic acid, chlorine, alkali metal chromate, alkali metal permanganate, alkali metal persulfate, alkali metal perborate, electrolytic oxidation. These several agents are the preferred oxidizing agents. Also there may be employed electrolytic treatment to provide the effects of oxidation.

The preferred forms of the oxidizing salts such as chromates, permanganates and persulfates are the sodium and potassium salts, but the ammonium salts may also be used and where available are included in the descriptive term alkali metal salts.

When chromate is used for oxidation of spent sulfite liquor, the chromate is added preferably as sodium dichromate, since this form is the most readily available in commerce, and in subsequent discussions the chromate addition is referred to as dichromate. However, it is well known that in aqueous solution chromate ions (CrO and dichromate ions (Cr O are readily interconvertible, depending on the pH of the solution. In strongly acid solution, the dichromate ion predominates, but on neutralization with alkali the dichromate shifts to the chromate. Equilibrium is readily reached between the two forms, depending on the pH of the solution. Therefore the chromate may be added as either chromate or dichromate.

One method of obtaining oxidation is by electrolysis whereby oxidation takes place at the anode of an electrolytic cell. We have found that effective electrolysis can be obtained in a simple cell with or without a membrane to separate the anode and cathode, and improved products have been obtained with current usages from 0.2 to 5.0 ampere hours per gram. The reducing effects at the cathode do not appear to alfect the results of the oxidation.

Oxidation by addition of sodium perborate results in contamination of the product with sodium borate which must be removed to obtain the greatest efficiency of the product. One method of purifying the product is to remove the resulting borate ions as calcium borate which readily occurs if the starting material is a calcium salt of sulfonated lignin containing material. The sodium perborate has an alkaline reaction and raises the alkalinity of the solution sufficiently to make calcium borate insoluble. The calcium borate may be removed by filtering or settling. Other methods known to those skilled in the art can be used for such purification. As set forth herein, chlorination also results in by-products of the reaction which should be removed by purification to obtain more effective products for drilling mud thinning.

in regard to the choice and use of oxidizing agents for practicing our invention, two factors are of prime importance: The strength or power of the oxidizing agent and the quantity of oxidant being used in proportion to the organic solids being oxidized. The strength or intensity of the oxidizing agent is expressed as an oxidation reduction-potential, and tables of these potentials are available in the chemical literature. Thus, we have found that the oxidizing agents which are suitable for carrying out our invention have a range of oxidation potentials greater than 1.3. The quantity of oxidant which is used to bring about the desired result may be expressed in a number of ways, for example, the weight in grams of each oxidant which can be used per grams of sulfonated lignin containing material, or the quantity may be expressed in terms of the available oxygen which is required to bring about the oxidation. To resume, the Weight of the particular oxidizing agent required to yield said weights of available oxygen can be calculated stoichiometrically. In the following table are listed the formula (molecular) weight, the weight of available oxygen available from the formula weight and the weights of the several oxidants necessary to give both 7 grams and 3 grams of available oxygen. Thus in the table is clearly shown the Weight of each of several oxidizing agents required per 100 grams of sulfonated lignin containing material to carry out the degree of oxidation with about 7 grams of available oxygen, or a more preferred degree of oxidation with less than 3 grams of available oxygen.

Above a degree of oxidation of 7 grams of available oxygen per 100 grams of sulfonated lignin containing material, the improvement of the mud is not appreciable, and the additive is not soluble on drying when the preferred oxidants, sodium dichromate, sodium permanganate, and chromic acid are used. On the other hand, our experience is that the addition of even small amounts provide improvement. On the latter basis, up to about 7 grams, and preferably up to about 3 grams of available oxygen per 100 grams of sulfonated lignin containing material provide the desired result. Parenthetically, let it be understood that 7 grams of available oxygen is a compromise figure because apparently the oxidation does not proceed entirely on the basis of chemical equivalency. Furthermore, some oxidants give incidental reaction products which at the higher usage are deleterious to the mud properties and counteract the eifects of the oxidation.

Further in regard to oxidation with chromium compounds: By experiment, we have discovered that oxidation of fermented spent sulfite liquor solids with sodium chromate at pH 8 provides a product which has substantially the same thinning effect on the drilling mud as a product obtained by oxidation with sodium dichromate at pH 4. In making this experiment both products were converted to the iron salt to make the mud test. Further-- more chromic acid may be used instead of the chromates in which case it is usually necessary to add sodium hydroxide to neutralize the product to about pH 4 to 5 prior to drying. All of these chemicals, i.e., sodium chromate, sodium dichromate and chromic acid give oxidized products, the iron, aluminum, copper and chromium salts of which are effective thinners for both lime and fresh water muds and give substantially similar results.

In summary, our invention is the discovery that oxidation plus forming a salt of a metal selected from the group of iron, aluminum, copper and chromium of the lignin sulfonate containing material provides an improved drilling fluid, and that the amount of oxidation can be greatly varied.

concentration in relation to each other.

1 3) it a Available oxygen In oxzdtzmg agents Weight Wt. C011- Wt. C011- Agent Formula Available taining 1 7 g. taining 2 3 g.

Weight Oxygen Available Available Oxygen Oxygen (7) (Formula wt). Wt. Av. Oxygen (3) (Formula wt.). Wt. Av. Oxygen 3 Equivalent oxidizing capacity.

The oxidided products are useful as thinners, and this is particularly important because products can be prepared from the original spent sulfite liquor merely by a simple oxidation process to give products equivalent as thinners to those prepared by more complex and expensive procedures. Furthermore, let it be particularly noted, essentially in precipitation and fractionation procedures only apart of the spent sulfite liquor solids are available for use as mud thinners while, in contrast, our invention and discovery makes use of substantially all of such solids. This point is important where yield and costs are of price consideration. Continuing then, if the product is to be used in other than so-called lime base drilling fluid, it is necessary to convert to the iron, aluminum, chromium, or copper salts.

The amount of oxidant required depends on the specific oxidant being used, the nature and purity of the sulfonated lignin containing material being treated and the conditions under which the treatments are conducted. In general and for practical operation, particularly respecting costs, 1% to 50% by weight of the several oxidants on thebasis of the dry sulfonated lignin containing material is all that is required to produce the desired result. However, when the oxidant is of a less concentrated character, as in the cases of alkali persulfate and perborates, both being costly, a larger percentage of such oxidant is required to obtain the desired result, as appears in the table above. In any case, the reaction should be conducted in such a manner and with concentrations and proportions of the reactants so that gelation of the solution does not occur and a permanently soluble product is obtained. Solubility of our additive product is a fundamental requirement because the product is to be added to a drilling mud system, one component of which is water in which the additive product must dissolve to function as a thinner by operating as a surface active agent. Also, the dissolving brings about the distribution of the agent uniformly throughout the medium which increases the effectiveness of the product.

By way of explanation gels contain some occlude-d water soluble product and to the extent that the water soluble component is available or the gel dissolves in the medium said gels function somewhat as thinners. If any thinning action occurs with gelled (i.e. insoluble) products, such thinning is deemed not to be due to the gel functioning as a surface active agent but is due to the soluble component accompanying the gel. At higher pH, i.e. above about 9, the unwashed gelled products dissolve to some degree and show some tendency to thin the mud. Particularly is this true if the dissolved component is not washed out. In any case gels are not desirable because the material is less efiicient.

Permanently stable solutions without gelation as shown in the examples may be obtained by conditions which slow the rate of reaction and keep the reactants in low Furthermore,

1 From the formula 2 From the formula other conditions a fecting the formation of gels in more or less degree are the degree of sulfonation, the concentration of the sultonated lignin containing material, temperature, concentration of the oxidant, pH and effectiveness of mixing. In addition, the character of the sulfonated lignin containing material being treated aiiects the amount of oxidant being used, in particular, the degree to which the materials have been previously purified, especially of reducing substance such as sulfur dioxide and carbohy drates, and/ or fractionated. The degree of sulfonation is important in regard to water solubility. Also, we have discovered that the molecular weight, and apparently the molecular weight distribtuion within the fraction will affect the quantity of oxidant required to bring about the desired result. By way of example and not limitation, when a 45% to 50% solution concentration of fermented spent sulfite liquor solids is being used as much as 15% or more of hydrogen peroxide may be added, whereas, with potassium permanganate or potassium dichromate, such concentration of spent sulfite liquor thickens rapidly to a gel when about 10% of these agents is added. Furthermore, by way of example to show the effect that the prior history or character of the spent sulfite liquor has on the quantity of oxidant which may be used without causing gelation, when a caustic treated fermented spent sulfite liquor as described in Example XIV is used at pH 4, about 8% of sodium dichromate will cause gelation at 42% total fermented spent sulfite liquor solids, 15 of sodium dichromate will cause gelling at 25% solids and 21% of sodium dichromate at 12% total solids, the dichromate in each case being added as a 25 solution in water at 60 C. Let it be noted that the above percentages are based on the weight of the dried fermented spent sulfite liquor solids being treated. Moreover under other conditions, even more of this oxidant can be added without causing permanent gelation or loss of water solubility. Purification and molecular weight are other factors which bring about gelation with difierent proportions of the oxidant. For example, using a solution of 45% to 59% total solids, about 4% by Weight of 1e solids of the oxidant will gel the purified high molecular weight lignosulfonates at a pH of less than 4.5, whereas, as much as 8% or more of potassium permanganate or sodium di chromate may be added to the low molecular weight lignosulfonate fractions of the same concentration without gelation. But substantially large concentrations of sodium or potassium dichromate may be added if the reactants are dilute. For example, a low molecular weight lignosulfonate fraction (40% of the total original fermented spent sulfite liquor solids) containing 17% of reducing substances expressed as glucose as a 2.5% solution in water treated at room temperature with 50% by weight of sodium dichromate as a 2.5% solution at a pH of 3 yielded after drying at room temperature a product which was slowly soluble in water. With 40% by weight of sodium dichromate the product was rapidly soluble in water. During such reactions the pH rises and acid such as sulfuric must be added to maintain the desired pH. The reaction under the above conditions was substantially complete in one hour. Thus the objective, namely a water soluble oxidized product, can be obtained with up to 50% by weight of the dichromate oxidant depending on the conditions used in the reaction as above disclosed. Similar results are obtained with potassium and sodium permanganate. The other oxidants which are less subject to providing insoluble products may also be used up to 50% and more by weight of the sulfonated lignin containing material depending upon said conditions.

Pilot tests We have discovered that the oxidants which are suitable for oxidizing the sulfonated lignin containing material rnay be roughly divided into two groups: Those containing the metal ions chromium and manganese, i.e. the alkali metal chromates and the alkali metal permanganates and those involving gaseous oxidation components, such as hydrogen peroxide, sodium persulfate, sodium perborate and chlorine and, accordingly, different tests were originally necessary in establishing the maximum amount of the oxidant which could be used for any particular sulfonated lignin containing material.

The maximum amount of oxidant particularly the chromates and permanganates which can be used with any one sulfonated lignin containing material can be determined by the following pilot test. A dissolved sample of the sulfonated lignin containing material is diluted to 2.5% solids, acidified to pH 3.0 with sulfuric acid for this particular test and various amounts of sodium dichromate added, together with sulfuric acid to maintain pH 3.0. The solutions are then allowed to stand about 1 hour at room temperature, adding sulfuric acid at intervals to maintain pH 3.0. At the end of 1 hour, the sample is heated to 80 to 90 C. and digested at this temperature for about an hour. The product samples are then dried at 60 C. and tested for solubility in water. The highest amount of dichromate giving a soluble product is the maximum limit of the amount of oxidant that can be used.

Another guiding test as to the maximum quantity of oxidant which may be used with any one sulfonated lignin containing material in forming the products of our invention and discovery is an evaluation of the performance of the product as a thinning agent for drilling mud. To apply this test, a solution of about 10 grams of sulfonated lignin containing material dissolved in 10 cc. of water is treated with 2 grams of ferric sulfate to convert the ligno sulfonate to the iron salt, the solution heated to 80 C. and centrifuged to remove calcium sulfate. This solution is then treated with various amounts of the oxidant being tested at a pH of about 3 to 5 for this particular experiment and heated at 8090 C. for about 1 hour and then dried at 60 C. The product is tested for solubility in water, as above, and then for mud thinning properties as described herein. If the properties of the base mud are not improved by the addition of the product, then too high a concentrate of that particular oxidant was used in the oxidation stage.

In any case, the maximum amount of oxygen which can be used is not greater than the equivalent amounts set forth in the table entitled: Available oxygen as oxidizing agents.

In using the oxidizing agents which involve a gas in the oxidation process, such as hydrogen peroxide, chlorine or sodium persulfate, a greater amount than that equivalent to sodium dichromate or sodium permanganate are required, since the use of such agents involves a more rapid deterioration and possible escapment of gas without complete reaction. it is probable also that the polyvalent metals manganese and chromium contribute to the efiectiveness of the final product and these are not present in said other oxidants. Therefore, while the equivalent proportions are a guide to the relative amount of oxygen that can be used, they are not exactly equivalent in regard to the improvement which equivalent amounts of each of the oxidants will produce in the product.

Optimum thinning properties appear to be attained with sodium dichromate usages which give solutions well removed from the point of gelation. For a fermented spent sulfite liquor, of 40% to 45% total solids, the preferred amount of oxidant is about 7% to 9% of sodium dichromate based on the spent sulfite liquor solids for overall performance respecting the several properties required in drilling mud, but especially low water loss characteristics have been observed with about 18% of sodium dichromate. On the other hand, with chlorine which is considered an oxidizing agent herein, substantially more than the other agents can be added because some of the chlorine reacts by substitution with the spent sulfite liquor components, so that additional chlorine is required to bring about the desired oxidation results.

The time and temperature of the reaction is important in that the reaction should be allowed to go essentially to completion and the product should be substantially free of gels. It is preferably that the oxidation be controlled to yield a solution which can be dried to a powder which can be redissolved in water. If the oxidation is too severe the solution may gel or the dried solids may not be water soluble. Potassium permanganate and potassium dichromate are very rapid in their action and usually the oxidation is complete in 5 to 20 minutes and thereafter the solution is stable and shows no visible evidence of change on standing. If 10% of these agents are added as a 25% solution to concentrated liquor of greater than 40%, the spent sulfite liquor will gel in 15 minutes at room temperature, or if the soltuion is hot, the gelation will occur almost immediately. Solutions more dilute in organic solids, permit the addition of higher percentages of these oxidants. With milder oxidants, such as hydrogen peroxide, 15 minutes to 24 hours are necessary to bring about the completion of the oxidation. The temperature is usually a matter of choice and convenience but should be such that the reaction is complete in the time provided, although lower temperatures will give less diifculty with local formation of gels.

The concentration of the spent sulfite liquor can be any concentration up to 70% by weight of solids, but it is desirable to have the concentration of the liquor low enough to promote homogeneous reaction and prevent subsequent gelation. However, for practical reasons, it is preferred to use solutions of as high concentration as possible and, preferably, of the order of 40 to 50% solids concentration. For this reason, the dilute solution of the oxidant is added to the cool spent sulfite liquor solution of 40 to 50% solids with intensive mixing and after the reaction has been more or less completed, the solution is heated to the temperature at which drying will be conducted.

Thus, it is clear that, because of the choice of oxidants involved in providing required properties, the varied nature of the sulfonated lignin containing material, and the many factors involved in the physical conditions under which the reactions can be conducted, and also the many well known types of equipment used in mixing the reactants, that it is not feasible to set forth the exact operating conditions for each product of production. Furthermore, the factor of what mud property is most desired must be considered since the properties do not respond in a parallel manner to all treatments. That is, sometimes all the properties may be improved where as in some cases only one of the properties may be improved. Accordingly, a selection must be made to obtain the desired result. But many examples are given in the herein disclosure which will enable persons skilled in the art to select conditions of treatment best suited to the particular requirement of the case in hand. But for most cases for use in the field the oxidants can be used in the concentration of 1 to 50% by weight of the Organic solids'as herein disclosed and thereby obtain a fully reacted and soluble product without gelation. The determination of the maximum amount of any given oxidant which can be used for any particular sulfonated lignin containing material is determined by pilot test as hereinbefore described. But the usage is one depending upon =which mud property is most desired. Ordinarily, it will be found that this usage is an amount of oxidant equivalent to less than 3 grams of available oxygen.

Special processing is necessary when chlorine is used as the oxidizing agent since in addition to oxidation and any other reactions'which occur, there is a reaction of chlorine withthe sulfite liquor components, and there are by-products from the reaction such as hydrochloric acid, which if left in the product may have a deleterious effect. For example, it has been found that on the addition of 1% to 4% of chlorine .on the basis of the dry weight of the spent sulfite liquor solids, the properties of the sulfite liquor residue improve even without further purification to remove the end products formed, such as calcium chloride. The chlorination can be increased, however, up to the addition of 45% of chlorine above which the chlorinated lignin tends to become insoluble andis therefore not useful where water soluble products are desired in drilling mud. For products having been treated with more than 4% by weight of chlorine, it is necessary to further refine them to remove the hydrochloric acid and reaction products of hydrochloric acid. One of the best methods of accomplishing this purpose is to precipitate the chlorinated lignin with lime. This treatment has additional benefit of purifying the lignosulfonates not only of the hydrochloric acid/and its end products, but also of the carbohydrates themselves. In this connection we have discovered that, whereas with regular spent sulfite liquor it is diflicult to divide the ligonsulfonates into several fractions by treatment with lime, surprisingly with the chlorinated lignins-of our invention and discovery, the products can be divided very readily into fractions of different average molecular weight. This finding has been of extreme usefulness in the preparation of specific fractions of the chlorinated lignin as to molecular weight.

While it has been known that lignosulfonates may be precipitated in mass from spent sulfite liquor by adding at one time relatively large quantities of lime slurry until a pH of 1l-l2 is reached, it is especially surprising and useful to have discovered that if the lignosulfonates be treated with chlorine then they may be readily divided by lime precipitation into many small fractions, while at the same time purifying the lignosulfonates from the carbohydrates, chlorides, and other miscellaneous components of the sulfite liquor. These oxidized and chlorinated lignosulfonates, fractionated as to molecular wei ht by lime, may then be used as such as lime base mud thinners, or they may be converted to aluminum,iron, copper, and chromium salts and as such they alsomake highly effective fresh water drilling mud thinners. Such oxidized and chlorinated lignosulfonates may be converted to other salts such as sodium magnesium, ammonium, etc., if calcium is objectionable in the product. Fractionation of the chlorinated spent sulfite liquor can also be accomplished by the alcohol fractionation process according to the disclosure of our application Serial No. 437,833.

In general, the products of our invention and discovery may be prepared from spent pulping liquor and the solids therein in the condition as received directly from the digester, or said products may be prepared from modifications of the said solid components of the spent pulping liquor. Such modifications may be provided by various treatments but, nevertheless, the resulting solids still do constitute soluble sulfonated lignin containing materials. By way of example and not limitation the treated solids may be as follows: They may 18.. be, asthey exist after fermentation of spent. sulfite liquor whereby the carbohydrate content is reduced or they may be as solids after hot spent sulfite liquor is acidified and air blown; or they may be obtained as set forth in US. application Serial No. 391,116, which briefly states the spent sulfite liquor treated with an inorganic base, for example sodium hydroxide, in developing a final pH of 7-10, the same may be heated at 40 to C. for a period of 30 minutes to 2 weeks, the solid organic components beingmaintained in solution throughout the said reaction period; or the spent sulfite liquor may be essentially freed of carbohydrates and extraneous material by any one of a number of procedures, preferably by fermentation or by adding increments of lime, or by precipitation,, dialysis, separation by organic solvents, and/or organic bases, or precipitated as basic lignosulfonate for example with lime, or by salting out with salts such as calcium or sodium chloride.

Furthermore, the .spent sulfite liquor components may have been derived by the pulping withagents other than the usual magnesium, sodium, ammonium, and calcium bisulfites. These other agents disclosed herein are iron and aluminum bisulfites.

Oxidation treatmentimproves the spent sulfite liquor components in providing a more effective lime mud thinner or more effective thinning and dispersing action in general, i.e., in both lime base and fresh water muds,

and also for other uses such 'as pigmentdis'persioni Base exchangeto-form iron, aluminum, chromium, or copper salts develops-fresh water mud thinning properties,

an improves some of the lime mud properties, as for example a base exchange with aluminum sulfate will yield a product with lower viscosity and gel characteristics in lime mud.

Oxidation gives improved thinning properties, while base exchange to iron, aluminum, chromium, and-copp.e r..

salts makes a fresh water mud thinner possible, With out the base exchange treatment a fresh water mud thinner is not obtained.

Relative calcium sulfate contamination Up to this point the disclosure has dealt primarily and especially with the treatment of the spent sulfite liquor components and with their fractionation, their treatment with metallicsalts, and the oxidation of said components, as Well as with the use of such spent sulfite liquor components in preparing well drilling muds in general, in establishing or proving first, that a change is made in said components by the treatment of our invention and discovery, and, second, that the magnitude of the. change is surprisingly great, as evidenced by the increased and augmented effectiveness of thetreated components as revealed in the preparation of such drilling muds.

Now the disclosure will relate. more specifically to the particular use of the said components in providing a product for controlling the colloidal and physical properties of gypsum base drilling muds so as to maintain them in the most desirable condition for use.

As one application of our invention we provide for muds where contamination is encountered from calcium sulfate (either as so-called gyp, or inithe anhydrite form, Portland cement, and similar calcium bearing material which would supply calcium ions which flocculate sodium bentonite as calcium vbentonite through base exchange reaction. This flocculation of the bentonite results in an increase in the. mud water loss. The water loss value of the drilling fluid may be 8 cc. at the time of entering a massive anhydrite section and 24 hours later be anywhere from 25 to 75 cc. if the mud is not treated properly. Anhydrite and cement differ in that the former supplies the sulfate radical alongwith the calcium while the latter supplies the hydroxyl radical which increases the fluid pH. The sulfate radical does not affect the pH of the solution although the pH ofthe mud may drop slightly 19 through replacement of the hydrogen ions from the bentonite particle by the calcium. The net efiect of the drilling of sufiicient anhydrite to saturate the mud aqueous phase with calcium is first to result in a marked increase of gel strength followed by a gradual increase in the water loss as the bentonite is converted to the calcium bentonite. As the calcium bentonite flocculates through loss of hydration properties, the gel strength decreases. The final result is a mud of high water loss, low viscosity and low gel strength. P. 25, Composition and Properties of Oil Well Drilling Muds, Rogers, Rev. Ed).

In case of contamination with calcium bearing strata, Rogers further states (beginning on p. 379 of said text):

The precipitation and removal of calcium from solution can be accomplished by at least four chemicals. These are:

1. Bentonite.

2. Soda Ash (Na CO 3. DiSodium Phosphate (Na HPO 4. Barium Carbonate (BaCO The first, the use of bentonite, is not very efficient but has been used in drilling anhydrite together with large quantities of thinners. It is not recommended for large quantities of calcium sulfate and will not be discussed further.

Soda ash is a common chemical precipitant for calcium sulfate. The reaction is:

In this reaction the calcium is precipitated as calcium carbonate while soluble sodium sulfate is formed and remains in solution. In this reaction 1.0 pound of soda ash will precipitate 1.283 pounds of calcium sulfate. The reaction goes to completion and excess quantities of soda ash are not required. The method has two disadvantages. The first results from high pH of soda ash. The compound in strong solution has a pH of approximately 11.2. The action of high pH in gelling bentonite mixtures has been shown previously. Since the pH of the mud will increase greatly from excess soda ash it is usually customary to use SAPP as a thinner because of its low pH value. The second disadvantage results from the continuing accumulation of sodium sulfate as calcium carbonate is precipitated. Any increase in concentration of such soluble salts acts to increase the gel strength. One of the main difiiculties with the soda ash treatment where thick beds of anhydrite are encountered is that the development of high gel strength from increased mud pH and sodium sulfate formation is so extensive that soda ash additions have to lag additions of thinner to reduce the mud pH and gel strength. As a result the calcium contamination continues to gain and the fluid loss continues to rise. It has been found impossible to maintain fluid-loss values below cc. when using this treating method to drill massive anhydrite. Where the contamination consists of stringers of short duration, soda ash can be used to handle anhydrite satisfactorily as its extent is not sufiicient to allow accumulation of sodium sulfate or the high pH condition.

Disodium phosphate as a chemical precipitant for calcium sulfate is similar in many respects to soda ash. The reaction with anhydrite is:

The products of the reaction are calcium phosphate, which precipitates from solution, and sodium sulfate and sulfuric acid which remain behind as soluble constituents. In this reaction 1.0 pound of disodium phosphate will precipitate 1.430 pounds of calcium sulfate. While disodium phosphate is slightly more eflicient, pound for pound, as a precipitant for calcium sulfate than is soda ash, its greater cost is a deterrent to its use for this purpose. The similarity with soda ash results from the single precipitation of the calcium with sodium sulfate as a residue. The divergence is largely in the pH difference of the two compounds. Disodium phosphate has a pH in strong aqueous solution of 8.6. The addition of this mildly alkaline compound to the mud does not result in as high gel strengths as obtained from soda ash. The residual quantities of sodium sulfate and acid act to increase the viscosity and gel strength of the mud. There are no data in the literature covering case histories of massive anhydrite drilled with this compound.

Barium carbonate makes a satisfactory chemical precipitant when drilling massive anhydrite. The reaction is:

CaSO +BaCO CaCO +BaSO In some respects this treatment is superior to that of soda ash or disodium phosphate. This results from the complete precipitation of "both the calcium and the sulfate radicals of the anhydrite as well as the barium and the carbonate of the treatment, leaving no soluble salts in solution. The barium carbonate is approximately neutral in pH and this in combination with the lack of residual soluble salts allows the mud to be restored to its original condition and allows low fluid losses and viscosities to be maintained while drilling anhydrite. The principal disadvantage of the method lies in the large quantities of material required and the resulting high cost. 1.0 pound of barium carbonate will precipitate only 0.691 pounds of calcium sulfate. In addition, the reaction is not very efficient as more barium carbonate must be used than called for by the reaction. Fortunately the addition of excess quantities of barium carbonate does not affect the mud adversely and overtreatment is primarily undesirable because of the cost of the barium carbonate so Wasted.

Thus, all these methods of overcoming the contaminant calcium sulfate fail, or are objectionable for one reason or another.

By way of summary, it may be stated that presently three methods of treatment are commonly used in the field to overcome the deleterious eifect of calcium sulfate:

(1) One method is to convert the mud to a limed mud by adding 3 to 5 pounds per barrel (a barrel being about 4-00 pounds) of hydrated lime, 1%. pounds per barrel of tannin, or 2 /2 to 3% pound-s per barrel of calcium lignosulfonate and then adding carboxymethyl cellulose and starch to control water loss. This method is expensive.

(2) Another method used is the employment of high pH red mud. The mud is raised to about pH 12 with equal parts of caustic and tannin, and water loss is controlled by addition of carboxymethyl cellulose. This method is also objectionable because it is expensive.

(3) A third method, and probably the most commonly used, is to convert to a gypsum base mud by adding 3 to 4 pounds gypsum per barrel of mud. The mud is thinned to the desired viscosity with water, and 4 to 6 pounds per barrel of starch added to reduce water loss, and A1 to /2 pound per barrel of a preservative added to prevent fermentation of the starch. This mud is objectionable because of the high flat gels which make the mud hard to pump in deep wells and make it difficult for cuttings to separate in the surface mud pits. Furthermore, by adding water, the volume of the mud is increased, and therefore part of the mud must be discarded to accommodate the capacity of the equipment. Also, because of the addition of water, the density of the mud is decreased and additional expensive weighting material must be added to increase the weight of the mud for deep drilling.

One of the outstanding features of using the product of our invention and discovery in preparing drilling muds. 15 to provide a method of controlling mud properties. against contaminants in drilling calcium sulfate bearing. strata which is less expensive and requires a minimum of effort and attention at the time such a stratum is encountered in the drilling, or when contamination by such, contaminants is anticipated. In fact, as. shown by Ex- 21 ample XIV, it may be only necessary to add 3 to 4 pounds per barrel of additional conditioner to the mud being used in the Well at the time the anhydrite is approached. N.B. Our product is particularly relatively inexpensive.

A further outstanding feature of the use of the product of our invention is the providing of a gypsum base mud with a low gel rate-that is, a mud with a low initial gel strength so that cuttings will settle out and be removed while the mud is flowing to and circulating in the mud pit, but with a sufiiciently high gel strength in the quiescent state so that sand and cuttings will not settle out in the well if drilling operations are temporarily interrupted for a period of ime. Hcretofore, gypsum base muds in common use have had high flat gels, that is, high initial and final gels. The viscosity of these muds increased as sand and fine cuttings accumulated, and it was necessary to maintain low viscosity by discarding some of the mud and bringing the remainder up to volume with water and bentonite. This treatment raised the Water loss and it Was necessary to add starch and carboxymethyl cellulose, which are expensive, to maintain a low water loss. By using a mud as in this invention, with a low initial gel strength without Watering-back, that is, the addition of more Water, the cuttings nevertheless do settle out in the mud pit, and also the maintenance cost of replacing discarded mud is eliminated.

In other words or by Way of summar the gypsum base muds utilizing the sulfonated lignin containing additives of our invention and discovery constitute a new drilling mud system of our invention and discovery. Heretofore, calcium sulfate contamination was eliminated by chemical means or the contaminated mud was discarded and new mud substituted. In combination with the additives of our invention calcium sulfate saturated muds, i.e. gypsum base muds, have very desirable drilling mud properties and also the high calcium ion content of these muds is effective in reducing the hydration of certain shales encountered in oil well drilling. This prevents the shales from swelling and closing the bore hole and the shale cuttings from making an excessive amount of thick mud.

Another desirable feature of our gypsum base muds is their thermal stability, a property essential for drilling deep wells in which high temperatures are encountered. These muds of our invention are characterized by their thermal stability at deep well temperatures.

A further important feature of the use of our products or additives is found in providing a mud resistant to gypsum contamination, which mud may be converted to an oil emulsion mud.

Still another outstanding characteristic of the use of the products or additives of our invention and discovery is found in the providing generally of muds with good thermal stability for drilling deep wells where high temperatures are encountered. Temperatures can very seri- 22 ously affect the necessary properties of the drilling mud, and therefore it is a very important property of the product and process of this application to provide thermal stability.

The treatment of the drilling mud according to our inventicn and discovery to control calcium sulfate contamination comprises adding a lignosulfonate thinner or additive which may be derived for example from spent sulfite liquor as hereinabove described, combined with sodium sulfate, said combination being formed in proportions of 1% to by weight of the sodium sulfate based on the said spent sulfite liquor solids, the most advantageous proportion being determined by a pilot test to determine about the proportion necessary to meet the particular situation developed by the drilling. In place of sodium sulfate, other salts such as iron sulfate, aluminum sulfate, sodium sulfite, potassium sodium tartrate, sodium oxalate, sodium phosphate, sodium carbonate, sodium bicarbonate and their corresponding potassium compounds, and mixtures thereof may be used. All of these compounds react with calcium sulfate to precipitate calcium and produce soluble sulfates. Regarding the use of bentonite clays, Rogers states, on page 378 of his text quoted above:

Sodium bentonite is a highly hydrated, dispersed and ionized member of the bentonite salts and possesses good fluid-loss reducing properties. Calcium bentonite, on the other hand, is poorly hydrated and dispersed and tends to fiocculate. This flocculation results in fewer but larger particles which tend to precipitate. As the calcium bentonite forms in increasingly greater percentage the agglomeration of the particles and precipitation result in a decreased viscosity and gel strengths and increased fluid loss properties. The formation of calcium bentonite results in depletion of calcium in the aqueous phase unless replaced by further solution of the contaminant.

Now that the general principle of operation of our invention has been stated, we will continue to present the details of the invention in more complete form, and the following next page is useful in showing the several courses whereby products of our invention and discovery may be obtained.

Any of the above products which are salts having an element selected from the group consisting of iron, aluminum, chromium, and copper may be further treated to improve their resistance to contamination (particularly to calcium sulfate as gypsum or anhydrite) by adding a salt in the amount of 1% to 100% of the spent sulfite liquor solids selected from the group consisting of sodium sulfate, sodium sulfite, potassium sodium tartrate, sodium oxalate, sodium phosphate, sodium carbonate, sodium bicarbonate, aluminum sidfate, iron sulfate and their corresponding potassium compounds and mixtures thereof, in providing a mud characterized by having low viscosity, low gel properties, and low water loss.

[Spent Sull'lte Liquor from Blow Pit and with optional treatment fermented and/or purified and/or fractionated and/0r concentrated to 20%70% solids (or preferably concentrated to 30%50% solids)] Fractionatc Manifestly, if the starting material was either raw spent sulfite liquor as it comes from the blow pit or if it was fermented spent sulfite liquor without further purification or fractionation, then any of the products of our invention as set forth in the above outline of the possible manifold treatments within our invention, may be further purified or fractionated by adding small increments of lime as herein disclosed or by phase separation, application Ser. No. 437,833. Let it be noted that fractionation has also important effects on the properties of the components of the spent sulfite liquor.

Thus, to follow through in detail, the starting material may be, as previously discussed, either the spent sulfite liquor solids as contained in the spent liquor as received from the blow pit, or these solids refined in various manners, such as by fermentation, lime precipitation, fractionation, etc. In any case, the solids to be treated are preferably concentrated to 30% to 50% solution. One method of operation, following from point (1 on the chart, is to treat the concentrated liquor with an acid and heat for example for 1 to 2 hours at 95 to 100 C. At this point if calcium sulfate is precipitated, it may be separated, depending on the purity desired in the final product. Said acid treatment may be carried out at less than about pH 4 at temperatures from 50 C. to 180 C. as more fully set forth in our co-pending application Ser. No. 723,036.

This product can be neutralized with a base such as sodium hydroxide (we mean a compound which yields hydroxyl ions in solution) to a pH above 3.5 so that it can be dried without degradation and then used as such as a limed mud thinner (2) without further treatment; or it can be further improved by oxidation, preferably with an alkaline reagent such as potassium permanganate or sodium dichromate which will yield a neutral product, as indicated at point (3) in the outline. Either product may be used as such; moreover, they can be reduced to solids by evaporation and drying. In either case, these products may be used as thinners for lime base muds. Alternatively, the product can be converted to the salt (3a) of iron, chromium, copper, and aluminum, and this is outstanding in the fact that it is operative very effective in both fresh water and lime base muds.

Again, the acid treatment may be carried out with an acid salt such as ferric sulfate, aluminum sulfate, chromium sulfate, or copper sulfate in such proportions as to also effect a base exchange (4) and yield a product which is effective for thinning both limed muds and fresh water muds. This product may also be oxidized (4a) as was the acid-treated product (1) to obtain further improvement in mud thinning properties.

Rather than treating with an acid as in (1), the concentrated liquor may be treated directly with an oxidizing agent as (5). In this case some of the oxidizing agent is required to oxidize the sulfur dioxide which escapes in the case of acid treatment. This oxidized product may be used as a lime base mud thinner, or it may be converted to the iron, aluminum, copper, or chromium salt as in (6) and used for thinning both lime base and fresh water muds.

Another pretreatment which gives improvements in the sulfonated lignin containing material preparatory to following the procedure of our invention is the heating of the solution of the sulfonated lignin containing material in water solution at highly elevated temperature and at a pH greater than 4 and preferably about 7 to 10. The heating is carried out for a short period of time of the order of 30 minutes at a temperature of about 200 C. At 220 C. the lignin is badly charred and is not suitable for further use for the purpose of making drilling mud thinners. This heating is conducted while blowing the solution with a gaseous medium such as air or nitrogen. Products prepared in this manner have improved properties, said improvement in properties being somewhat equivalent to those attained by our process of acid treatment as described in our US. Ser. No. 723,036.

Another and highly effective procedure is to follow the process outlined in our application Ser. No. 391,116 involving treatment with alkali. This product (7) may then be acidified either with an acid (8) and oxidized (9), whereby a lime base mud thinner is obtained, or further processed to form the aluminum, iron, copper, and chromium salt (10). Instead of acid, aluminum, iron, copper, and chromium sulfate may be used through which an economical and effective spent sulfite liquor additive (11) is produced, the properties of which may be greatly enhanced by oxidation with any of the oxidizing agents previously mentioned, to yield (12) an extremely etfective agent for conditioning drilling fiuids of the fresh water, lime base, and oil emulsion types.

NB. We have discovered that spent sulfite liquor components, or such components chemically modified in their separation from spent sulfite liquor, or in their preparation (i.e., we find that materials identified in general as lignosulfonates respond favorably to our treatment) are greatly improved in their effectiveness as dispersing agents and for use in drilling muds by treating them with one or both of the following steps:

(1) Oxidizing said spent sulfite liquor components.

(2) Treating to form a salt having an element selected from the group consisting of iron, aluminum, chromium, and copper.

The order of the above steps or treatment (oxidizing or forming a salt) is immaterial.

Continuing our treatment against contamination by calcium sulfates, the product resulting from both steps 1 and 2, or the product of step 2, is treated with a salt in the proportion of 1% to of the lignosulfonate solids of said spent sulfite liquor solids, selected from the group consisting of sodium sulfate, sodium sulfite, potassium sodium tartrate, sodium oxalate, sodium phosphate, sodium carbonate, sodium bicarbonate, aluminum sulfate, iron sulfate, and their corresponding potassium compounds and mixtures thereof.

Method of testi;zg.Specific examples of treatment, together with tables showing results of tests of the ma terials, will now be set forth. The method of making the tests is that commonly followed in the drilling industry.

The sulfonated lignin additives of our invention may be used in many ways, but chief among these is that revealed in drilling muds. For this purpose a material is required which will bring about a lowering in viscosity of the complex clay suspension which is termed the drilling mud, and will also serve to decrease its gel strength and water loss characteristics. The accepted methods for evaluating materials to ascertain their utility for drilling muds are described in the publication entitled American Petroleum Institute Code 29, Third edition, May 1950 Recommended practice on standard field procedure for testing drilling fluids. This manual is prepared and published by the American Petroleum Institute, Division of Production, Dallas, Texas, and is used throughout the industry for testing drilling muds.

In mak ng the laboratory tests on drilling muds according to the procedure mentioned above, it is necessary to use a clay or combination of clays. In general, clays are of extremely wide distribution in the earths surface and are complex and difiicult to define chemically. For

example, H. A. Ambrose, PhD. and A. G. Loomis, PhD., state regarding drilling mud clays: analysis tells us little with respect to the properties required in drilling. There has been no correlation between chemical analysis and clays and their suitability for drilling purposes, The Science of Petroleum, volume I, page 458, 193 8, Oxford University Press (London). Although clays have been divided into several classes according to their chemical and physical form, the materials encountered or used in drilling muds are mixtures of said clays and so it has become practically accepted to define these materials in terms of What is termed yield value. According to practice then (Principles of Drilling Mud Control, 8th edition pages 2 and 3, published by the American Association of Oil Well Drilling Contractors, Dallas, 1951) clays are defined in terms of yield value, Which is the number of barrels of 15 cp. mud that can be prepared from a ton of material alongwith water. Thus in the examples, we refer to the use of natural clay and define the yield value to characterize the type of clay which would give similar results.

By following the standard methods identified above and using plays of defined yield Value, the efficacy of the sulfonated lignin additives of our invention is measured in terms of initial gel strength, viscosity, ten-minu e gel strength, and water loss.

The Stormer viscometer has been used almost universally in making viscosity measurements according to the standard methods of the American Petroleum Institute. Also let it be noted that another means of measuring viscosity is a motor driven rotational viscometer known as the Fann V-G meter (viscosity-gel). This instrument measures two factors of viscosity called yield value of fluids and plastic viscosity which are so related that two times the plastic viscosity plus the yield value is proportional to the viscosity at 600 r.p.m. Since the plastic viscosity is essentially constant for any one mud, the variation of the yield values indicate directly the variation of viscosity and therefore the yield value is reported in the tables where the measurements were made With the Fann instrument.

Generally'only the yield value of the drilling mud is affected by the addition of thinners. Yield values are reduced by drilling mud thinners but plastic viscosity is affected very little. The plastic viscosity can only be changed by adding to or removing water from the mud. The Faun V-G meter type of instrument is preferred for drilling muds since it indicates whether thinners are needed to lower yield or whether water is needed to decrease plastic viscosity.

The viscosity factor yield value of fluids defined above should not be confused with yield value of a clay which has been defined hereinabove as the number of barrels of 15 cp. mud that can be prepared from a ton of clay along with water.

Mud test procedures.The following mud test pro-v cedures describe in detail the mud preparation and testing procedures used. The clays defined in the test pro-. cedu-res given below were used in all of the first twelve cial rotary drilling clay with a yield value of 45 barrels f 15 centipoise mud per ton of clay were mixed with 325 milliliters of distilled water in a Hamilton Beach No. 30 Drinkmaster mixer for 15 minutes at 15,000'r.p.-m.,

and then aged by rolling, i.e., agitating in pint bottles.

26 overnight at room temperature. The aged mud was broken over to a limed mud by adding 6 grams of calcium hydroxide, 6 milliliters of sodium hydroxide solution containing 0.25 gram sodium hydroxide per milliliter, and the sulfonated lignin containing material additive to be tested (each gram added equivalent to 1 pound per barrel) and mixing for 5 minutes at high speed. Broken over is a term used in the industry to denote the procedure and the accompanying change in properties which occur when an excess of calcium hydroxide and sodium hydroxide is added to a clay with intimate mixing as next above set forth. The mud was then returned to the bottle and again rolled overnight at room temperature, and finally mixed another 5 minutes immediately before determining viscosity, gels, and water loss by the standard procedure of the American Petroleu-m Institute.

Fresh water mud test pr0cedure.Thirty grams of a commercial sodium bentonite rotary drilling clay with a yield value of 92 barrels of 15 centipoise mud per ton of clay were mixed with 335 milliliters of distilled water in a Hamilton Beach No. 30 Drinkmaster mixer at 15,000 rpm. for 15 minutes and then aged by rolling overnight in pint bottles at room temperature. The thinner additive (each gram-added equivalent to 1 pound per barrel) and sodium hydroxide to give the desired pH were then added, the mud mixed 5 minutes, and again rolled overnight at room temperature. A final 5 minute mix was made immediately before measuring viscosity, gels, and water loss by the standard methods of the American Petroleum Institute. The mud may be returned to the bottle and rolled a further 24 hours at 150 F. and then retested to obtain information'on the effect of temperature. Higher temperature aging is described in Example XVII.

Gyp mud test pr0cedure.The gyp (or gypsum base) mud test procedure is the same as the fresh water mud test procedure except that 6 grams (each gnam added equivalent to 1 pound per barrel) of plaster of Paris (CaSO /2H O) were added together with the thinner additive, and the mud was subsequently mixed for 20 minutes instead of 5 minutes.

Oil emulsion test pr0cedure.T he base mud is prepared as described above and may be any of the types such as lime base, gypsum, fresh Water and salt water muds. After adding the thinner additive being tested and making the standard tests for gels, viscosity and water loss, 10 to 20% by weight of diesel oil is mixed into the mud with a high speed mixer at 15,000 rpm. and the resulting oil in water emulsion mud tested for gels, viscosity and water loss by the standard API procedures. Note that the term thinner is used in the art in reference to agents or additives for reducing the viscosity of drilling mud.

EXAMPLE I This example illustrates the procedure for fractionating spent sulfite liquor by lime precipitation to obtain calcium lignosulfonate fractions with better drilling mud thinner properties than the original spent sulfite liquor.

One thousand grams of spent sulfite liquor solids in 10% water solution were heated to about C. and lime slurry was added grams of calcium oxide), whereupon an appreciable amount of organic precipitate was obtained. (Temperature not critical, 85 C. equals term perature of liquor as received from blow pit.) The small precipitate settled rapidly and was separated by decanting and recovered as a cake by centrifuging the thick slurry. Further fractions were recovered successively in the same manner by adding 25 gram increments of lime and removing the precipitates formed. The precipitates 2? were washed by decantation with saturated lime water to prevent resolution by water during washing, then redissolved by adding sulfuric acid to pH 5 to 6 and dried after removing by filtration calcium sulfate. Results of the fractionation are shown in Table 1.

TABLE 1 OF EXAMPLE I Fractionation of spent sulfite liquor by lime precipitation Cumulative Lime Added, Yield of Percent of Calcium Diffusion Fraction No. Spent Sulfite pH Llgnosulfonate, Coelhcient,

Liquor Solids Percent of mmF/day Originally Spent Sulfite Present in Liquor Solids Solution 13. 10. 2 14. 4 5. 8 15. 5 l0. 8 4. 5 6. 5 18. 0 11.3 10. 0 7. '3 20. 5 l1. 8 4. 6 8. 7 23.0 12. l 4. 6 9. 7 25. 5 12.2 4. 7 10. 4

In redissolving, other acids than sulfuric may be used in lowering the pH of the separated precipitate and bringing about solution. It may be preferred to use an acid such as carbonic, sulfurous, or oxalic, which are characterized by giving insoluble compounds with calcium whereby excess calcium is removed from the product. In some types of drilling mud, it is desirable to have the additive as free as possible of soluble salts, so that acids such as hydrochloric and acetic which form soluble calcium salts would not be desirable, although for some purposes they could be used. Also the precipitate can be dissolved by adding a salt which gives by base exchange an insoluble calcium salt, i.e., sodium, iron, chromium, copper, aluminum, magnesium ammonium, etc. sulfates, phosphates, oxalates, sulfites, etc. Thus the desired iron, copper, aluminum, and chromium salts can be made directly.

It will be understood that any fraction will dissolve if the pH is lowered below the pH at which it was precipitated, but the addition of sulfuric acid to provide pH 5 or 6 is helpful in giving quick solutions and approximately neutral products. Thus, we have discovered that it is possible to divide the lignosulfonates of spent sulfite liquor into several fractions by adding as the first step a relatively small or minute amount or an increment of lime, that is, 130 grams in 10,000 grams of spent sulfite liquor of 10% concentration which caused to precipitate an appreciable, i.e., recoverable, amount of organic precipitate, namely 14.4%, and also we discovered, contrary to expectations, that said amount settled out surprisingly rapidly. This precipitate was separated out as fraction No. 1. Then, as a second step a small amount or increment of lime, i.e., grams (CaO) was added to the remaining solution, whereupon a second small amount, 4.5% of the original spent sulfite liquor solids, was precipitated and this likewise rapidly. This was separated. Successively the above steps were repeated until six fractions were removed.

Differences in drilling mud thinner properties of the 28 fractions, the molecular weights of which are illustrated and identified in T able 2 of Example I.

TABLE 2 OF EXAMPLE I Limed mud tests on fractions of spent sulfite liquor prepared by lime precipitation Initial 10 Gel, Water Fraction No. Lb./bbl. Gel, gins. Visc. gins. Loss,

Original Spent Sulfite Liquol 4 29.0 250 21. 9 4 20 43. 2 30 10. 7 4 0 15. 0 60 14. 0 4 0 9.8 40 14. 2 4 0 11.0 60 15.0 4 0 12. 3 100 15. 3 4 10 14.0 1G. 2

Table l of Example I shows that the calcium lignosulfonates were fractionated into fractions of different molecular weight as shown by the diffusion coefficient data. Table 2 of Example I shows that fraction 3 was the most effective drilling mud thinner because of the greatest reduction in the properties noted which particularly means that less water is required to give a pumpable mud drilling fluid with a minimum of water loss all of which properties are of most fundamental importance in oil and gas well drilling. Of course, the fractionation may be varied by adding smaller amounts of lime to give smaller fractions characterized by having more uniform molecular weight distribution, or a fraction may be made including parts of fractions 2 and 4 in fraction 3. Thus is made most manifest the wide scope, advantages, and flexibility of our invention and discovery.

Also, this example illustrates that our invention and discovery teaches that by proper manipulation the organic precipitate can be obtained between pH 10.0 and 12.0 from spent sulfite liquor upon adding lime, and can be recovered as a number of calicum lignosulfonate fractions of different molecular weights. We also have discovered that these different fractions exhibit different improved properties, thereby making it possible to select the improved fraction in suplying a product exhibiting the exact or more nearly exact properties required for a particular application.

EXAMPLE II To illustrate the improvement in drilling mud thinner properties obtained by chlorinating spent sulfite liquor according to our invention and discovery, samples of fermen-ted spent sulfite liquor were concentrated to 30% solids by evaporation and then commercial chlorine gas was bubbled into the liquor until weight increases corre sponding to l, 2, 3, and 4% of the solids of the fermented spent sulfite liquor solids were obtained. Samples chlorinated with 1% and 2% chlorine had pH 3.2 and 2.6 respectively and were dried at 60 C. The 3% and 4% chlorinated samples had pH 1.4 and 1.0 respectively and were neutralized to pH 2.0 with sodium hydroxide before drying at 60 C. to avoid deterioration of the components of the spent sulfite liquor. The dried samples were tested as limed mud thinners and the results are set forth in Table 1 of Example II.

Chlorination of a fermented spent salfite liquor LIMED MUD TESTS USING 6 POUNDS PER BARREL Limed Mud 10% Diesel Emulsion Percent 01 in Spent Sultlte Liquor LG. Vise. 10 G. W.L. LG. Vise. 10 G. W.L.

13. 0 60 18. 2 12 29.0 180 10. 0 13.0 17. 8 O 33. O 70 10.0 0 11. 0 20 17. 7. 0 30. 2 60 10. 0 0 9. 8 5 16. 5 0 27. 7 9. 7 O 9. 8 3 17.2 5 O 26. 5 35 9. 5

LIMED MUD TESTS USING 4 POUNDS PER BARREL 65 25. O' 195 19. 1 Thick In all cases of chlorinating, the pH should be, adjusted by the addition of an alkali before dryingto a value of more than 2.0 and less than 10.0.

Table 1 of Example II shows-a progressive improvement in mud thinner properties as the percentage of chlorine is increased, up to 4% chlorinew When lessof the additive is added to the mud, some of the mud thinner properties of the sample chlorinated with 4% chlorine are poorer than obtained with the sample chlorinated with 3% chlorine. Thus, it becomes necessary'to purify chlorinated spent sulfite liquor (i.e. for example, remove calcium chloride) when more chlorine is used than 4%, otherwise better products are not obtained.

EXAMPLE III To illustrate the fractionation of a chlorinated spent TABLE 1 OF EXAMPLE III Fractional lime precipitation of chlorinated lignosalfonates from chlorinated spentsulfite liquor sulfite liquor by lime precipitation a sample of spent- By comparison with Table 1 in Example I it is seen that the chlorinated lignosul fonates begin precipitating at a much. lower pH. than the calcium lignosulfonates of.

The resulting wide pH.

the original spent sulfite liquor. range of precipitation makes possible a closer control of fractionation reproducibility than is obtainable with lime precipitation of spent sulfite liquor solids.

Comparative drillingmud tests were made on thefractions of Table 1 of Example III as shown in the following table:

TABLE 2 OF EXAMPLE III Comparative limed mad. tlzil'zningproperties of chlorinated ligno sulfonate fractions obtained by lime precipitation Limed Mud 10% Diesel Emulsion Sample LbJbbl.

I.G.- Vise. 10 G- W.L. I. G. Vise. 10 o W.L.

Original Fermented Spent Sulfite Liquor (before Chlorination) 4 25.0 195 19.1 Thick Fraction2 4 0 as 0 15.5 0 27.'.5 9.4

Fraetion3 4 '0 11.0 10 16.9 o' 25.0 9.8

Fraetiou4 4 5 13.5 i 40 18.8 50 39.5 200 11.5

6 o 8.5. 10 20.8 0 I 20.0 I 80 11.6

The spent sulfite liquor chlorinated with 43% of chlorine before fractionation and Without purification to remove calcium chloride on addition to lime base mud gave a thicker mud than did untreated fermented spent sulfite liquor.

The data of Table 2 of Example III show that the chlorination of the spent sulfite liquor by passing of chlorine gas through spent sulfite liquor renders the spent sulfite liquor components especially effective in conditioning lime base muds. Particularly are they effective in increasing the thinning property, as will be seen by noting the results respecting viscosity for fractions 1-4. All of said fractions are improved over the original spent sulfite liquor viscosity figure of 25.0. Fraction 2 shows a viscosity of 9.8 which is the preferred result. Thereafter, fractions 3 and 4 show an increase in viscosity which indicates that the fraction 2 gives the Optimum result in lowering viscosity. Referring to the other properties of fraction 2 in comparing these with the other properties of the fractions 1, 3, and 4, it is to be noted that the properties of fraction 2 are optimum. In other words, it is not only to viscosity that fraction 2 gives optimum results, but in general to other properties. In addition, it is noted that these fractions are highly effective in producing oil emulsion type muds and whereas the optimum properties occurred with fraction 2 for the regular lime base drilling mud in making oil emulsion type lime base muds, the fraction 3 gave the greatest lowering in viscosity although fraction 2 itself was highly eifective as compared with either fraction 1 or 4 or especially the original sulfite liquor.

The outstanding teaching of Table 2 of Example III is that it shows that different fractions of the spent sulfite liquor have varying properties and therefore that it is of the utmost importance, in using spent sulfite liquor where definite properties are desired, to fractionate said liquor and determine which fraction will give the best properties for the particular problem in hand. The chlorination treatment is thus seen to play a very important part in providing fractions of the spent sulfite liquor. It greatly facilitates the procuring of such fractions, and furthermore, the very important feature is revealed that the fractions of the chlorinated product are of a greatly improved character. In other words, the eflectiveness of the lignosulfonate components is greatly increased by chlorination.

EXAMPLE IV To illustrate the yields of chlorinated lignosulfonates obtained by lime precipitation purification of chlorinated spent sulfite liquor by the addition of varying amounts of chlorine to 45% fermented spent sulfite liquor, the following table is presented.

TABLE 1 OF EXAMPLE IV cent of original spent sulfite liquor solids Chlorine used in chlorination, percent of spent sulfite liquor solids:

iflgield includes chlorine combined with spent sulfite liquor S0 1 S.

The data of Table l of Example IV show that for chlorine usage up to about 30% of the spent sulfite liquor solids the cost of chlorine addition is compensated by an increased yield of product in amount approximately equal to the weight of chlorine added. Moreover, such chlorine addition gives an improved product. Furthermore, the table shows that the addition of more chlorine over the 30% figure does not provide additional yield.

In general the chlorination can be conducted in diluted, i.e. in the spent sulfite liquor as received from the blow pit, or in concentrated spent sulfite liquor.

EXAMPLE V The improvement in thinning action in lime base mud provided by oxidation of spent sulfite liquor solids with several oxidizing agents is shown in the following example: Solutions of 100 grams of spent sulfite liquor solids in 300 milliliters water were mixed cold with solutions of the various oxidizing agents to give the concentrations of oxidizing agent based on spent sulfite liquor solids shown in Table 1 of Example V. The solutions were then heated at C. for one hour to insure complete reaction, dried at 60 C. in a flat shallow pan and ground to a powder for testing. The results of adding these powders to lime base muds are shown in the following table. In these experiments a lime base mud was prepared as described herein above using a clay having a yield value of 45. In all cases the results involve the addition of 4 pounds of the powdered product per barrel of mud.

TABLE 1 OF EXAMPLE V Effect of oxidized spent sulfite liquor on lime based mud Sample LG. Vise. 10 G. W.L.

Original Fermented Spent Sullite Liquor 29. 0 250 21. 9

3% H202 (hydrogen peroxide) 60 20.0 200 20. 2 6% H202 30 I5. 20. 2

2% KMnOi (potassium permanganate) 65 24. 0 230 18. 5 4% KMJ104 35 18. 7 190 17. 4 6% 7 16. 2 150 18. 4 8% KMDO-i- 0 l5. 0 130 19. 0 4% K2Cl'207 (potassium diehromate)- 85 25.2 280 19. 6 6% zClzO 15 20 17. 3 10 16. 5 150 17. 6 30 22. 5 15. 8

4% NagOz (sodium peroxide) 75 26. 5 250 19. 0 6% NazOg 50 19. 0 260 19. 6

Table 1 of Example V shows improvements in mud thinning obtained by oxidation with several oxidizing agents. In further experiments beyond the scope of said table We have discovered improvements in lime mud thinning for products from fermented spent sulfite liquor oxidized with hydrogen peroxide up to 50% by weight.

While a greater weight percent of potassium dichromate than of hydrogen peroxide or sodium peroxide, i.e. 8% as compared with 6%, is required to reduce the viscosity to a comparable level, the relative cost of these materials is such that the use of potassium dichromate is much more attractive economically. Furthermore, the potassium dichromate gives a greater improvement in water loss than the other oxidizing agents listed in Table 1 of Example V.

Whereas chlorine is an oxidizing agent and has been so referred to hereinabove, and it is a very inexpensive chemical relatively speaking, however its use requires further purification of the oxidized and chlorinated spent sulfite liquor solids by the use of lime precipitation. In contrast, the oxidizing agents listed in Table l of Example V may be used without such purification step, i.e., without resorting to the lime precipitation step. Thus, our discovery includes the use of hydrogen peroxide, potassium permanganate, potassium dichromate, sodium peroxide and other agents as set forth herein, which are characterized by their efficiency in oxidizing the components of spent sulfite liquor to give the results of mud conditioning properties.

EXAMPLE VI This is an example of the conversion of calcium base spent sulfite liquor to an aluminum base lignosulfonate mud thinner for fresh water, or sodium bentonite muds.

TABLE 1 OF EXAMPLE VI Thinning of fresh water mud by calcium and aluminum salts of spent sulfite liquor LG. Vise. 10 G. W.L.

Original Mud 80 52. 170 9.2 1.5 lb./bbl. Calcium salt 5o 52. 5 170 8. 4 1.5 lb./bbl. Aluminum salt 35. 0 240 8. 4 1.: 111/1001. Quebraclm 25 4o. 3 130 7. 3

While spent sulfite liquor as received from the blow pitcontains calcium salts, nevertheless such salts provide little or no thinning action for the mud. This fact also has been observed for ammonium, magnesium and sodium salts of the lignosulfonates. On the other hand, Table 1 of Example VI shows that the aluminum salt is comparable to quebracho under the conditions of the test.

It is academic that quebracho is the preferred material for use in conditioning fresh water muds (being used to the extent of 30,000 to 40,000 tons per year for such purpose), and accordingly, to provide a product which is comparable from a waste product like spent sulfite liquor, is a meritorious contribution to the art.

While this illustration of Example VI has been directed to the contrasting properties of the aluminum salt with those of the usual so-called cooking bases, calcium, ammonium, sodium, and magnesium, similar results have been observed with the iron, copper and chromium salts as set forth in the following example, namely VII.

EXAMPLE VII To illustrate the preparation of iron, chromium, copper and aluminum salts employing as the starting material the spent sulfite liquor additive of our invention (US. patent application Serial No. 694,737) the following examples were prepared and tested as follows:

The spent sulfite liquor additive, i.e. the additive solids, were prepared as follows: 1000 grams of concentrated calcium base spent sulfite liquor derived from paper production and having the carbohydrate removed by fermentation and having an alkalinity value about pH 4, containing 47.5 pounds of dissolved solids per 100 pounds of solution, were treated with 74 grams of sodium hydroxide (containing 50% by weight of sodium hydroxide) at 80 C. with mild agitation for hours. The pH was then 7.9. For the preparation of each salt, 211 grams of this solution was diluted with 89 cc. of water to make a solution and reacted with solutions (25 in Water) containing 20 grams of aluminum sulfate (17% A1 0 20 grams of ferric sulfate (Fe (SO .9H O), grams of copper sulfate (CuSO .5H O) or 20 grams of chromium potassium sulfate respectively, and the resulting precipitates of calcium sulfate were filtered off. The products were dried at 60 C. and tested as fresh water mud thinners using 1.5 pounds of thinner per barrel of mud.

and chromium salts of spent sulfite liquor additive, U.S. upplicaliOn Serial No. 694,737

pI-I Agent Added I G Vise I 10 G W L Original Mud (No agent) 52. 5 170 9. 2 Aluminum Salt 3 31. 5 400 9. 9

9.5. Iron Salt; 7 30. 3 140 7.0 Chromium Salt 10 35.1 7. 7 Copper Salt 5 37.0 8. 7 Quebracho 20 40. 5 170 7. 9 Original Mud (No agent) Very thick; too thick to measure. Aluminum Salt 50 63.0 4.50 8. 7 Iron Salt 5 27. 7 7. 2 12.0 Chromium Salt. 0 22. 5 100 7. 5 Copper Salt 0 25. 5 130 8. 0 Quebracho 5 21. 5 7. 5

It is clear from these results that thinning action is obtained with all of these salts of the spent sulfite liquor components comparable with that of quebracho in fresh water muds at a pH of both 9.5 and 12. Although the aluminum salt does not show appreciable thinning at a pH of 9.5, it does provide substantial thinning at pH 12. The preferred salt, based on its efliciency as a thinner, is the iron salt, although in muds having a pH of 12 the chromium salt shows even more enhanced properties, i.e. it provides a product with more effective properties, particularly in that it gives a greater viscosity lowering for a given concentration.

Further, it is to be noted that whether or not these products are to be oxidized or prepared from spent sulfite liquor or oxidized spent sulfite liquors, some acidity is developed during base exchange and must subsequently be neutralized as hereinhefore described in Example VI. In this case it is therefore advantageous to add the sodium hydroxide to the spent sulfite liquor first by way of preparing our additive according to US. application Serial No. 391,116 which thereby provides a more desirable starting material and at the same time provides the sodium hydroxide necessary for the final neutralization.

EXAMPLE VIII To illustrate the effect of the degree of oxidation on the fresh water mud thinning properties of iron salts of fermented spent sulfite liquor solids, a number of samples of iron salts were prepared as described in Example VII and then oxidized by heating for one hour at 95 C. with 2, 4, 6, 8 and 10% of potassium dichromate before drying at 60 C. The results of fresh water mud tests made at pH 12.0 with 0.5 pound of thinner per barrel are as follows: (the pH 12 was chosen for these tests because muds of this pH are generally more difficult to thin).

TABLE 1 OF EXAMPLE VIII Effect of degree of oxidation of thinner on fresh water mud thinning Oxidation (Percent LG. Vise. 10 G W.L. Potassium Dichromate) The data of Table 1 Example VIII shows improvement through continued decrease in viscosity of the fresh water muds at pH 12.0 as the degree of oxidation increases up to 10% of sodium dichromate. The concentration of spent sulfite liquor solids affects the amount of oxidant which can be advantageously added without formation of an insoluble gel. In this experiment, sodium dichromate was added as a 25% solution in water sfierv to spent sulfite liquor having a total solids concentration of about 40% by weight. Thus, a continued improvement in drilling mud thinner properties was discovered and this effect oi increase of oxidant is shown Furthermore Table 2 of the starting material, no salt such as chromic sulfate or ferric sulfate was added to give fresh water thinning properties. The sulfuric acid added to maintain pi-I 3.0 was sulficient to precipitate the ca.cium as calcium sulfate. The latter was removed but does not necessarily in Table l of Example VIII. Example VIII illustrates that Water soluble products were have to be removed for etfective use in gyp-mud. Calobtained with much larger amounts of oxidant by adding crurn sulfate should be removed for use in fresh water dilute solutions of the oxidant to dilute spent sulfite mud. liquor. Table 2 establishes that the improvement in The product liquors as set forth above were heated to drilling mud thinning properties continued as the amount C. to insure completion or" the oxidation and then of oxidant increased to about 14% of sodium dichrornate. dried at 60 C. for testing. At this point the viscosity of the mud being tested be- The oxidized products were tested as thinners for a gan to increase Whereas the Water loss continued to degypsum base mud using 6.0 pounds per barrel of thinner crease to an adidtion of about 18% of the sodium dito compare their relative value as mud thinners and as chromate. Thus, the Water loss factor continued to 15 Water loss reducing agents. The mud test results, Table improve at least to 18% sodium dichromate addition. 2 of Example Jill, show the water loss results improve Moreover at 50% sodium dichrornate addition the treaton increasing th sodium dichromate to about 18%. ed mud is appreciably beneficiat-ed comparison with the Mud thinning r ts become poorer above 7% of sountreated gypsum mud. dium dichromate, but said oxidized products are oper- TABLE 2 OF ERAMPLE VH1 20 able as drilling mud thinners over the range of 1% to of sodium dichromate. Range dick/017ml? An especially useful effect of using larger amounts of The following experiments were made to illustrate the f f dlchmmali l i l iHWYOf/ed l To effect of varying dgrass Oxidation on gypflmd high temperatures. This errect is shown 111 Table 3 wnere thinning properties of iron salts of fermented scent sul- Pf' p 9f nmds til-133% Wllh -QP P g fite liquor solids. Samples Were made using various OI lbs 591111119135 PmPm'ed abeve with 4% amounts of sodium dichromate and tested as drilling of 50 dlcmonfiia TZSPZCUVEIY are compfmd mud thinnel.s sum base mud art-er aging the mud for 20 hours at The preparation was started by making a quantity of g r 1 a I evaporated, fermented spent suliite liquor alkaline to pH i last i [F1016 Show P SMPPIC 8 with sodium hydroxide, and then heating in an open pfiliparlim w OI sodium dlchmlfmie mammal on container at 80 to 90 C. for 24 hours, While adding agmg yhdda and Walter 9 Wngmas the sflmple sodium hydroxide at intervals as needed to maintain the i f i 14% of Sodium dlchl'gmate actually pH at 8.0. Next 15% of ferric sulfate (24.5% Fe) Was 9 In weld gels f agng at and dld not added as a 30% solution followed by 4% of sulfuric acid lmmagg as much 1055- A $691211 and dflmand added as a solution in wmsl. and finally 7% Cf mg need for mud thinners stable to high temperatures has scdium dihydrate was added as a sohfion Wiih been recogmzed as higher temperatures were encountered vigorous agitation at a temperature of C. All addion deep drillingtions are based on the weight of the fermented spent A TABLE 2 1: EXAIr/QLE VH1 sulfite liquor solids. The mixture was heated to C. FL; in a hot Wat ham and cemfifuggd t0 rcmova is pmci? eer 0 amount of socuztm (Zzchron arc carnation itate of calcium sulfate. The clarified liquor was then flmlmlg propel?! ivided into several parts, each diluted to 10% solids [Untrwtsd yu- 1,Yie1 19.0,API WatcrLoss 32.4 and 10% solutions of sodium dichromate added to increase the dichromate to l4.0, 18.0, 20.0, 21.0 and 24.0% 45 Percent i o PQYC9I1CH11 M 11 Yi l API Water respectively by weight of the said spent sulfite liquor ltll g fljfiiii Plow l g fii rf fifi tlf ii solids. Sulfuric acid was added to control the acidity at pH 3.5 while adding the sodium dichromate. 2 5 3. 5 9. 4 Two additional samples were prepared with the addi- 55- Q9 8.1 tion of 40% and 50% of sodium dichromate to a sample 1:? ii of fractionated fermented s ent sulfite liquor solids con- 9 2 taining 17% of reducing substances determined as glucose {58 and the remainder of the spent sulfite liquor solids predominantly low molecular weight lignosulfonates. Said TABLE 3 OF EXAMPLE Vlll Thermal stability at 350 F.

Sample #mbl Rolled Overnight. Room Temp. Aged 20 Hrs. 350 1- p11 LG. PV Y 10 G. W.L. pII LG. PV Y 10 G. W.L.

4% Dichromate 4.0 8.2 2.0 0.0 8.0 14.0 10.0 8.2 22.0 0.0 30.0 43.0 2&0 14% Dichroinato 4. 0 s. 2 3. 0 5. 5 0. 0 9. 0 8. 4 7. 5 1. 0 0. 0 1. 0 7. 0 18.3

PV=plastic viscosity. Y=y valuesample of fractionated spent suh'ite liquor was obtained by alcohol fractionation. The sodium dichrornate was added as a cold 2.5% solution to cold 2.5% solution of the said spent sulfite liquor solids while adding sulfuric acid to maintain the pH at 3.0. Since the high dicnromate usage results in chromium ion concentrations equivalent to the addition of ess chro l uni still to over that necessary ror base ex c of the calcium in EXATJPLE IX This example illustrates on the one hand, the improvement in fresh water mud thinner properties and, on the ot; er, the poorer results obtained in limed muds by adding an excess, more than the amount of iron, aluminum, copper or chromium sulfate necessary to base ex.- change the calcium in spent suiiite liquor solids. Spent sulfite liquor solids (about 40% concentration) were 37 oxidized with 8% of potassium dichromate by heating in aqueous solution at 95 C. for one hour. Two samples or portions of said oxidized spent sulfite liquor were prepared, one was mixed with 20% (base exchange) and the other with 35% by weight of aluminum sulfate (17% A1 It will be noted that about 23% is equivalent for base exchange. Thus, the second sample had an excess over base exchange of about 12%. After filtering off the precipitate of calcium sulfate, the products were dried at 80 C. and tested as fresh water and limed mud thinners. The results are shown in the following table:

TABLE 1 OF EXAMPLE IX Efiect of the amount (i.e. concentration) of aluminum sulfate on thinning properties [Fresh water mud test using 0.5 lb. per bbl. at pH 9.5]

It is apparent from these figures that the effect of the concentration of aluminum sulfate added in making the aluminum salt on the thinning properties of the product is different for fresh water muds than for lime base muds. In the case of fresh water muds the initial gel and viscosity are both improved, that is, lowered, whereas in the limed mud, the excess makes the properties poorer. Manifestly, if the product is to be used only in fresh water muds, the product having the excess of alumlnum sulfate is preferred, but if the product is to be prepared for use optionally in either fresh water or llme base muds, then the equivalent, or the amount of aluminum sulfate necessary for base exchange of the calcium, would be preferred.

TABLES 2 and 3 OF EXAMPLE IX The following example illustrates the improved drilling mud thinning properties in both fresh water and gypsum mud resulting from the addition of an excess of iron sulfate, chromium sulfate, aluminum sulfate or copper sulfate over that required for a base exchange in spent sulfite liquor. Aluminum in Table I of Example IX and non in Table 2 of Example IX have been chosen as illustrating the effect of all four metals above.

For example, fermented spent sulfite liquor was reacted with various amounts of ferric sulfate (24.5% Fe) from 15% to 80% by weight of the spent liquor solids. The ferric sulfate was dissolved in water to make about a 30% solution and then poured into the hot concentrated (about 48% total solids) spent liquor with stirring. After digesting overnight at 8590 C. the acid mixture was neutralized to pH 4 by adding lime slurry, centnfuged to remove calcium sulfate, and dried.

The dried products were tested as mud thinners in both fresh water and gypsum base muds. These muds were prepared as hereinbefore described using 45.5 lbs. per barrel of a mixture of clays containing 6 parts of a commercial drilling clay having a yield value of 45 barrels of 15 cp. mud per ton of clay and one part of a commercial drilling clay having a yield value of 95 barrels of 15 cp. mud per ton of clay.

In the case of the fresh water mud test two pounds per barrel of the sample was added to the mud and sufficient sodium hydroxide added to adjust the pH of the mud to 9.5 and mixed for minutes on a high speed mixer. The muds were then placed in sealed glass bottles, rolled overnight at room temperature and finally heat aged by rolling for 20 hours at 150 F. The muds were then tested for yield values and gels by the standard API test method. The test results are shown in Table 2 of Example IX. To test the samples in gypsum mud, 4 lbs. per barrel of the sample together with 6 lbs. per barrel of plaster of Paris were added to the water suspension of commercial drilling clay, described in Example XIV. These muds were adjusted to pH 8.2 by adding sodium hydroxide and mixed for 20 minutes on the high speed mixer. The muds were then placed in sealed bottles, rolled overnight at room temperature and heat aged for 20 hours at 150 F. The samples were then tested for yield values and gels. The test results are shown in Table 2 of Example IX.

With reference to Table 2 of Example IX, it is shown that substantial improvement is attained in both fresh water and gypsum base muds by the addition of excess ferric sulfate, and that the greatest improvement in all properties is attained in the range 20% to 60% addition of ferric sulfate (24.5 Fe) on the fermented spent sulfite liquor solids. This addition is equivalent to about 17% to 52% of the anhydrous ferric sulfate, the lower figure being a little more than required for base exchange. The choice of the percentage employed is determined by the particular property most desired.

About 17.7% of ferric sulfate (24.5% Fe) is required to completely base exchange iron for calcium in the spent sulfite liquor and the amount added above 17.7% is therefore excess ferric sulfate above base exchange. That the excess iron is bound chemically by the spent sulfite liquor solids can be shown by the failure of iron to precipitate when solutions of the test samples are made alkaline by the addition of sodium hydroxide. The product therefore appears to have the characteristics of a complex salt. Thus, although we speak of the metals being present as cations, because of the possibility of the formation of a complex salt, the metals may not be entirely present as cations. But in any case, the metal is present in soluble form and we herein refer to these metals as being present as cations.

Similar results were obtained with ferrous sulfate in place of ferric sulfate.

TABLE 2 OF EXAMPLE IX Efiect on thinning properties of increasing the concentration of ferric sulfate Ferric Sulfate Addition Yield Value of 10 Minute Gel Water (Percent of SSL Solids) 1 Mud (lb/100 (lb/100 sq. ft.) Loss, ee.

sq. It.)

Test With Sodium Base Mud:

54. 0 107. 0 l2. 0 35. 5 48. 0 l0. 7 34. 0 52. 0 9. 4 20. 5 41. 5 9. 2 l5. 0 43. 0 9. 0 18. 0 42. 0 l0. 5 29. 0 66. 0 '11. 4

1 SSL=spellt sulfite liquor ill this case fermented.

TABLE 3 OF EXAMPLE IX The limit of the addition of the sulfate salts of iron, aluminum, copper and chromium to the oxidized salts is different for each salt, because it varies for each metal and also with the degree of hydration of the sulfate salts. To obtain an indication of the maximum amount of these salts which can be added an experiment was made in which oxidized spent sulfite liquor samples were prepared containing the chemical equivalent of these salts to excess of ferric sulfate (24.5% iron). The excess means the amount of salt over that required to bring about the 

1. A WELL DRILLING COMPOSITION COMPRISING AN AQUEOUS SUSPENSION OF A CLAYEY MATERIAL CONTAINING AN EFFECTIVE DISPERSING AMOUNT OF A SOLUBLE, COMPLEX INORGANIC PHOSPHATE SALT AND A SOLUBLE, OXIDIZED SALT OF A SULFONATED LIGNIN-CONTAINING MATERIAL, SAID SALT HAVING A CATION SELECTED FROM THE GROUP CONSISTING OF IRON, ALUMINUM, CHROMIUM, COPPER AND MIXTURES THEREOF, SAID PHOSPHATE SALT BEING PRESENT IN AN AMOUNT SUFFICIENT TO SUBSTANTIALLY REDUCE THE VISCOSITY OF THE DRILLING FLUID, AS MEASURED ON A STORMER VISCOSIMETER AT 600 R.P.M., BELOW THAT OBTAINED WITH THE ADDITION OF EQUAL AMOUNTS OF EITHER THE COMPLEX INORGANIC PHOSPHATE SALT OR THE SULFONATED LIGNIN-CONTAINING MATERIAL ALONE.
 6. A WELL DRILLING COMPOSITION COMPRISING AN AQUEOUS SUSPENSION OF A CLAYEY MATERIAL CONTAINING AN EFFECTIVE DISPERSING AMOUNT OF A SOLUBLE, COMPLEX INORGANIC PHOSPHATE SALT AND A SOLUBLE SALT OF A SULFONATED LIGNINCONTAINING MATERIAL, SAID SALT HAVING A CATION SELECTED FROM THE GROUP CONSISTING OF IRON, ALUMINUM, CHROMIUM, COPPER AND MIXTURES THEREOF, SAID PHOSPHATE SALT BEING PRESENT IN AN AMOUNT SUFFICIENT TO SUBSTANTIALLY REDUCE THE VISCOSITY OF THE DRILLING FLUID, AS MEASURED ON A STORMER VISCOSIMETER AT 600 R.P.M., BELOW THAT OBTAINED WITH THE ADDITION OF EQUAL AMOUNTS OF EITHER THE COMPLEX INORGANIC PHOSPHATE SALT OR THE SULFONATED LIGNIN-CONTAINING MATERIAL ALONE. 